Showing papers in "Japanese Journal of Physiology in 1958"

The interaction of electrical activity among neurons of lobster cardiac ganglion.

Abstract: 1. The potential changes were recorded from the individual large cells of the lobster cardiac ganglion with the aid of intra-cellular microelectrodes. Special attention was paid to the interaction among the cells, and, using a dual beam oscilloscope, simultaneous recording was made from two different cells.2. The “follower” type of potential was the most common and similar to that obtained in ganglion cells of an American lobster, described by Hagiwara and Bullock (10), and Bullock and Terzuolo (7).3. The synaptic potentials in two adjacent cells were closely synchronized. This seems to indicate existence of common presynaptic fibers. On the other hand the superimposed spikes were not always synchronized.4. With an inward current applied to the cell membrane, the spike generation was often blocked. On the other hand, however, the synaptic potentials were increased in amplitude.5. An outward current applied to the cell membrane caused a depolarization. With sufficient strength a spike or a series of spikes was produced superimposed on the depolarization.6. Electrotonic potentials were elicited by an applied current, not only in the cell in which the current electrode was inserted, but also in a neighboring cell in which no current electrode was inserted, with a reduced amplitude and a delayed time course. This phenomenon was regarded as existence of “electrical connections” among large cells.7. In some specimens when the small cells were anaesthetized with 0.1% procain-sea water, a slow oscillatory potential change was produced in one of the large cells, which has variable amplitude of up to 10 mV and frequency of about one per second, and was superimposed with a spike or a series of spikes. 8. The slow oscillatory potentials appeared in a neighboring cell with a certain phase shift and a reduced amplitude. This phenomenon was explained as a sort of electrotonic spread which is made possible by the electrical connection among cells.

The long-lasting depression in neuromuscular transmission of frog

Abstract: 1. When the double indirect stimuli more than 70 msec. apart were applied to the partially curarized frog muscle, the second action potential of the muscle was smaller than the first one and the depression lasted more than 10 sec. The depression was also observed in the twitch height of the uncurarized gastrocnemiusmuscle in vivo.2. The magnitude of depression of e.p.p. after a conditioning stimulus was about 10-15 per cent and its time course was quite similar to that of the partially curarized muscle action potential.3. The time course of depression of e.p.p. was exponential and its time constant was 4-5 sec. at 25°C.4. Lowering the temperature decreased the magnitude of depression and lengthened the time course. Q10was about 1.7 in the range of temperature 15-25°C.5. Calcium deficiency and an addition of magnesium to Ringer's solution decreased the size of depression. In calcium rich solution the size of depression augmented but its time course was the same. Potassium and eserine had little or no effect on the magnitude and time course of depression.6. The lengthening of muscle increased the depression.7. The increase in number of conditioning stimuli augmented the depression but had little effect on its time course.8. Repetitive stimulation of low frequency caused the decline of the amplitude of successive e.p.p.'s, and the rate of decrease was much more slower after five or six responses.

On the intestinal intrinsic reflexes.

Abstract: In dogs, cats and rabbits decerebrated under anesthesia or nonanesthesia, the intrinsic reflexes were studied in the denervated small intestine. The results are summarized as follows:In dogs, cats and rabbits decerebrated under anesthesia or nonanesthesia, the intrinsic reflexes were studied in the denervated small intestine. The results are summarized as follows:(a) When the surface of the mucosa was mechanically rubbed with brush or cotton-wool, or stimulated chemically with 0.1 normal solution of HCl, halfsaturated copper sulphate solution, mustard paste or crystals of sodium chloride, the excitatory state was elicited on the oral side of the stimulated region, giving rise to an increase in the strength of normal rhythmic contractions, while the inhibitory state on the anal side, eliciting a decrease in the strength of rhythmic contraction waves. This excitatory state might be occasionally so exceedingly enhanced that the ascending waves are elicited from the stimulated region. The reflex responses were elicited after the degenerative section of the mesenteric nerves concerned, while they were abolished after administration of hexamethonium.(b) When the muscular coats were mechanically stretched or chemically stimulated, i.e., with acetylcholine, histamine, pilocarpine or BaCl2 the rhythmic contraction waves were inhibited on both sides of the stimulated region. The administration of hexamethonium as well as the degenerative section of the mesenteric nerves concerned had no influence upon the reflex responses.(2) The discrepancies among the results obtained by previous authors would be chiefly due to the mode of stimulation, having the tendency of both the mucosal and muscular reflexes being invoked at the same time. Furthermore it was observed that the reflexes described above might play an important role to realize the polarity observed on the motility of the small intestine.

The effect of temperature on the neuromuscular junction of the frog.

Abstract: 1. The effect of temperature on the neuromuscular transmission of the frog's sartorius muscle was studied, with the intracellular electrode, at temperatures between 10°C. and 20°C.2. The end-plate potential diminished, in general, in amplitude as the temperature was lowered. The rate of change in the amplitude was large in the condition that the output of the transmitter from the nerve endings was reduced.3. The probability of appearance of end-plate potential recorded from the preparation soaked in a solution of a low calcium and high magnesium concentration was smaller at lower temperature.4. The effects of temperature on the time course of end-plate potential were considerably great, not only on the rising phase (Q10=2.7), but also on the falling phase of end-plate potential (Q10=2.2). The falling phase of polarized membrane potential was little influenced by temperature.5. The time course of displacement of total charge during the end-plate potential was remarkably lengthened at lower temparature.6. In the eserinized end-plate potential the temperature change had little effect on the falling phase, but the rate of change in the amplitude was greater than that of the non-eserinized end-plate potential.7. The frequency of the spontaneous miniature end-plate potentials had a considerably high temperature coefficient, the mean Q10 being 4.0.8. From these results it may be concluded that an increase in the amplitude of the end-plate potential at higher temperature is mainly due to an increase in output of the transmitter from the nerve endings, and the relatively high temperature coefficient of the falling phase of the end-plate potential is due to a prolongation of transmitter activity at lower temperature.

The critical depolarization for the spike in the squid giant axon.

Abstract: (1) The potential change across the membrane of the squid giant axon during passage of electric current is investigated using internal longitudinal stimulating and recording electrodes.(2) The threshold condition for constant current pulse is determined by the electrical constants of the resting membrane when the duration of pulse is short (less than 2 msec. at about 16°C.). For longer currents, up to 5 msec.(at about 16°C.), some amount of subthreshold potential change contributes to the condition. In both cases the critical depolarization for the spike shows the same value which is called the resting critical depolarization.(3) Shifting the membrane potential to various levels with short current pulses it is concluded that the critical depolarization is a certain potential level at which the dV/dt immediately following changes its sign and is often followed by a plateau potential which represents an unstable equilibrium potential level.(4) The minimal gradient for stimulation with a linearly increasing current is mainly determined by delayed rectification of the membrane while the late phase of accommodation is due to the increase of the critical depolarization.(5) There are two certain current intensities for producing two spikes with a constant current. The one limits the longest interval between them and the other limits the shortest one. Delayed rectification is mainly concerned with the existence of the former and the increase of critical depolarization contributes to the latter.

The fish eirg in response to different types of illumination

Abstract: 1. The fish EIRG (Svaetichin's cone action potential) was investigated on Cyprinus auratus with several types of illumination.2. The response amplitude depended strongly upon the area illuminated, becoming very small when the diameter of light spot was decreased to 0.2 mm.3. During passage of the border of light and dark across the site of recording, no abrupt change occurred in the response amplitude.4. Illumination by monochromatic light whose wave-length was changing continuously through the visible spectrum produced various response curves from different regions of the same retina. The result appeared to confirm Svaetichin and Motokawa et al., but details could not be compared due to the difference in experimental conditions.5. Based on the above results, the nature of the response was discussed.

ON THE SITE OF ACTION OF γ-AMINOBUTYRIC ACID ON BLOOD PRESSURE

Abstract: Experiments were performed on rabbits, dogs and cats and the followingresults were obtained.1.γ-Aminobutyric acid caused fall of blood pressure accompanied with a slight bradycardia.2. This acid had no direct action on the heart and the vessel following the administration of the dose effectual sufficiently on blood pressure.3. The blood vessel of the spleen actively dilated.But, this dilatation of the vessel in the spleen did not take place after the denervation.4. The severance of the cervical vagi, the cervical sympathetics, the depressor nerves and the denervation of the carotid sini on both sides had no effect on the action of this acid on blood pressure. Bradycardia was more or less lessened, but the compelte disappearance hardly occurred by the section of the vagi.5.γ-Aminobutyric acid showed no inhibiting effect on the superior cervical sympathetic ganglion of the cat. But, after the almost complete blockage of ganglia caused by tetraethyl-ammonium bromide or hexamethonium bromide, this acid affected no longer blood pressure.6. In decerebrate animals, this acid showed the same effect as in the intact animal.7. The latency of the fall of blood pressure was the shortest, when γ-aminobutyric acid was injected in the vertebral artery. The latency in the internal carotid injection was much longer than in the intravenous injection. The latency in the internal carotid injection was of the same order as in the injection into the subaxillary artery.8. The intracisternal injection of γ-aminobutyric acid caused more marked and sustained fall of pressure than the intravenous injection. The inhibition of respiration became more evident. Bradycardia also took place.9. The region of the central nervous system responsible for the effect of this acid was determined by means of transection of the brain stem and partial elimination of the medulla. The results revealed that the caudal part of the medulla was the concerned region.10. The distribution of the points that responded with a fall in arterial pressure to topical application of this acid accorded with that of the depressor points stimulated electrically in the medulla.11. The microinjection of γ-aminobutyric acid in the medial reticular formation of the medulla caused fall of pressure. The microinjection in the area postrema caused also fall of pressure. The minimal effective dose in microinjection was 0.5 μg in 10-3 ml.12. It is inferred that γ-aminobutyric acid acts on the depressor points in the medulla and causes fall of blood pressure.

The diffusion of oxygen inside the red cell.

Abstract: For the clarification of the diffusing capacity in the lung, the diffusion of oxygen inside the red cell was theoretically studied under more general conditions than hitherto considered as to the combination of oxygen with hemoglobin, and as to the initial and boundary conditions. The concise expression of the diffusion rate of oxygen dζ/dt was therefrom obtained as follows:where ζ represents the average oxygen concentration, t, the time, Pa and P the average oxygen tensions in the plasma and the red cell respectively, and F1, the newly derived coefficient, a function concerning the saturation of oxyhemoglobin.On the other hand, the oxygen tension Pc corresponding to the saturation of oxyhemoglobin in a dissociation curve is usually used instead of P. In such a case, the coefficient F2 in an equation similar to the above one gives such characteristics different from F1 as, that when hemoglobin is saturated with oxygen and hence the combination rate decreases, F2 tends to zero, while F1 approaches to a certain value other than zero.The above-stated fact affords new information for the treatment of the diffusing capacity of the lung, DL, as follows. DL as well as F2 must clearly represent the rate of oxygen combination with hemoglobin inside the red cell rather than the rate of oxygen diffusion. Furthermore, the diffusing capacities of both oxygen and carbon monoxide in the lung are well compared with each other by the use of the coefficients, F2 (O2) and F2 (CO).

Seasonal changes in human body fluids.

Abstract: Seasonal alterations of distribution and amount of water and salts were studied on adult male subjects at basal condition and following results were obtained.1) The serum water content increases in summer and decreases in winter, while the serum protein concentration and the hematocrit present reverse changes.2) The total circulating serum volume as well as the blood volume also undergo the same course of seasonal changes. The serum volume is higher in summer than in winter by 8.6% of the annual mean, and the change of blood volume is mainly effected by that of serum volume.3) As the total circulating serum protein is maintained almost constant throughout the year, the above mentioned seasonal changes are mainly due to hemodilution in summer and hemoconcentration in winter by changes of water content in circulating serum.4) The total body water (TBW), the extracellular fluid (ECF) and the intracellular fluid (ICF), all increase in summer and decrease in winter. The percentage change of ECF is the most remarkable among the others, while theabsolute amount of ICF change approximately coincides with that of ECF change, because ICF is far higher in its absolute volume than ECF. The seasonal change of water amount in circulating serum seems to be mainly effected by the change of ECF.5) The water metabolism, including the intake of water and its elimination from the body, increases in summer and decreases in winter and thus the water balance is maintained at zero level in each season after the acclimatization has been attained. Seasonal change of total water output is mainly due to that of the total perspiration (insensible water loss sweating), which undergoes a similar change, while the urinary output changes reversely.6) The ADS content in serum increases in summer and decreases in winter, while the level of osmotic pressure in serum presents a reverse change. From these, it is presumed that the central regulatory mechansim of water metabolism, including the functions of the osmoregulatory centre and pituitary gland, is put in function to conform to seasonal change of water elimination, especially of perspiration.7) Seasonal variations of serum water, ECF, ICF and TBW can be explained by this postulation of climatic adaptation of water metabolism. The seasonal variation of urinary excretion can also be explained by this change of central control of water metabolism, i.e. change of water reabsorption from kidney due to seasonal change of ADH secretion.8) Na, Cl and K concentrations in serum show also seasonal variations, decreasing in summer and increasing in winter. The change of K concentration is far larger than the other two, and thus the ratio of Na/K increases in summer while it decreases in winter.9) The total Na and Cl contents in circulating serum and as well as in ECF increase in summer and decrease in winter, while the total K content in both compartments changes reversely. From these, it is suggested that secretion of mineral corticoid may undergo a seasonal variation.

Brain-stem representation of jaw muscle activities of the dog.

Abstract: 1. The electromyographic discharges of rigid jaw mucles in the decerebrate cat were dominant in the suprahyoid muscle groups and scanty in the jaw closing muscle groups. But the jaw closing muscles were sensitive to stretching and showed strong spastic resistance to even a slight opening of the mouth.2. In spite of the marked extensor rigidity of the limbs, jaw rigidity disappeared readily after decerebration at a level caudal to the mesencephalic trigeminal nucleus.3. Regular spontaneous unit discharges were recorded from and along the mesencephalic trigeminal nucleus and root of the dog. The background activity in these points was remarkably depressed by elevating the lower jaw and accelerated by depressing the jaw. These responses were obtained by strictly localized punctures in the brain-stem, accompanied by a short latency and slow adaptation as shown in goat by Cooper, Daniel and Whitteridge.4. Nearly the same response was recorded in the lateral bulbar reticular formation at points just caudal to the cerebellar peduncles. There were also some localized points in the medial bulbar reticular formation near the hypoglossal nucleus at level rostral to the inferior olive, in which the background activity was inhibited by opening of the mouth.

The dependency of the diffusing capacity on the HbO2 saturation of the capillary blood and on anemia.

Abstract: The diffusing capacities DL's of oxygen were measured in dogs at various inspired O2-tensions and at various red cell numbers in the circulating blood in order to compare two capacity components, that is, the red cell component DB and the membrane component DM.DB is related to the average HbO2 saturation of the capillary blood, the red cell concentration, the cardiac output and the contact time as theoretically investigated in the previous paper. Hence, the authors compared DM and Dr, or DL and DB with each other by using the relations both between DB and HbO2 saturation, and between DB and the red cell number, because DL measured can be expressed asFrom the results it was shown to be highly possible that DM is at least three to four times as great as DB, so that one could practically put DL=DB. It was further made clear that the contact time became c. 0.18 sec. on an average in dogs in case DM=∞.

Oxygen consumption in relation to thermal sensation on cold exposure.

Abstract: Experiments were made to study the regulatory mechanism of body temperature during cold exposure and the main emphasis was laid on the relation of reactions against cold, particularly of an increase in heat production, to thermal sensations.1) When a lepromatous patient with a wide-spread dermal lesion where thermal sensations were extensively affected was exposed to cold, the patient complained little, unlike a healthy control, of the cold for the first several minutes. The body temperature of the patient was steadily falling and after about 15 minutes when the fall of the temperature exceeded 1°C., the patient began to suffer a chill and oxygen consumption showed a marked increase.2) When the rectal temperature of a healthy man was lowered with a cold water bath the threshold of warmth on the flexor surface of the forearm suffered no change as long as the skin temperature was maintained at the same level, while the threshold of hot pain became higher distinctly and the threshold of cold pain became lower.3) Reactions in each stage of cold exposure leading to death was observed in an unanesthetized rabbit.A) EEG's of the cortex (the postcentral area), subcortex and thalamus showed very similar pattern though taken from different levels of the brain. The electrical activity of the brain was discussed in relation to EMG and heat production, and an introduction of some momentous change was highly conceivable at the rectal temperature level of 28-26°C.B) Sensory EEG arousal response revealed that the ascending reticular system was hyperresponsive in a rectal temperature zone of 34-30°C. and below it the system reacted less by degrees.C) The frequency of EEG from the sympathetic zone began to increase below the rectal temperature level of 37 or 36°C. A peak which was reached at 33-30°C. was followed by a progressive decrease. As to the parasympathetic pattern the frequency did not show an increasing tendency till the rectal temperature fell down below 33-31°C. A peak of increased frequency at 28-27°C. was followed by a gradual decrease. A transient rise was observed on both EEG's in the excitation stage before death.Based on these experimental findings some interrelationship on introduction of reactions to cold was discussed among the somatosensory cortex, ascending reticular system and autonomic nervous center.

Initiation of contraction by transverse and longitudinal current flow in single muscle fibers.

Abstract: 1. The membrane potential and the tension development of a single muscle fiber of a toad or a frog were recorded simultaneously and their causal relation was investigated.2. In normal saline the occurence of action potential was followed by the all-or-nothing contraction, the peak of which was attained in about 100 msec., the maximum value of the tension developed varied between 20 and 80 milligrams (temperature 12°C.).3. In isotonic choline chloride solution the threshold for local contractions was about 40 mV in fibers of 90 mV resting potential. The contractions were graded with the stimulus intensity, maintained during the flow of the current. Tensions of several milligrams were obtained. The threshold membrane potential was approximately proportional to the resting potential.4. In procain-Ringer solution the longitudinal current through the fibers could be raised up to 3 ×10-6 A without eliciting contraction. In the case of fibers in normal saline this critical stimulating current was about 2 × 10-6 A. These critical values were explicable by the leakage membrane current due to the finite internal resistance of the fiber.5. Considering the estimation that the strength of the normal action current did not exceed the value of 0.8×10-6 A it was concluded that the longitudinal current inside the muscle fiber does not initiate contraction, and that the only indispensable factor is depolarization of the membrane.

Two components involved in galvanic skin response.

Abstract: 1. The potential changes of galvanic skin reflex usually consist of negative (hand becomes more negative) and positive deflections.2. With intense or successive stimulation, the amplitude of negative deflection increased at first and then positive deflection grew step by step in size. Finally the negative deflection was invisible.3. Lying on one side inhibited not only the positive but also negative de flection in the same side.4. Local ischemia abolished the positive deflection.5. Local cooling and warming gave inhibitory and facilitatory effects on GSR respectively.6. From these results it is concluded that GSR is composed of two basic elements, i.e. negative and positive processes. The characters of these processes are discussed.

Regional difference of the direct cortical response.

Abstract: 1. The cortical response to electrical stimulation applied to the cortical surface was investigated in the rabbit with particular attention to its regional difference. Three types of response corresponding to cortical areas were distinguished.2. The first type of response consisted of a surface-positive potential of 5-10 msec. duration followed by a surface-negative one. On the positive potential were superimposed two positive spikes and a sequence of three inflections. The distribution of the response was limited to area striata of Rose.3. The second type consisted of a surface-positive potential of 3-5 msec. duration followed by a surface-negative one. The surface-positive potential was preceded by one or two positive spikes. The distribution of the response extended over regio postcentralis and regio parietalis of Rose.4. The third type consisted of a simple surface-negative potential of 5-10 mesc. duration. It was distributed over regio praecentralis and area retrosplenialis granularis dorsalis of Rose.5. The potentials of these three types changed in amplitude as well as in form according to intensities of stimulation, but could be distinguished from one another above a certain level of intensity.6. A pick-up needle electrode was inserted into various layers of the cortex to record responses at different depths. Positive and negative deflections and positive spikes of the first and the second types of response reversed in sign at a certain depth characteristic of each. The sign reversal of the positive spikes took place in deeper layers than that of the positive deflection, and the layer in which the negative deflection reversed was found deepest. Before the sign reversal of the positive deflection took place, a marked phase shift was observed in the first type, but not in the second type. With the third type any conventional sign reversal could not be observed in most cases.

Diffraction spectra produced by the rabbit cornea.

Abstract: The diffraction spectra of the rabbit cornea have been studied in polarized light between crossed and parallel polaroids as well as in ordinary rays.The clear diffraction spectra were observed between crossed polaroids with a small amount of light scattering. The scattering increased considerably when observed between parallel polaroids or in ordinary rays.It is suggested that the anisotropic corneal fibers and the isotropic interfibral spaces build up a diffraction grating.The grating element distance was 13-15μ.The spectra became somewhat obscure on stretching. They disappeared on compressing and reappeared on removing the strain.The grating element distance increased irreversibly on swelling, but was influenced only slightly by drying.

Conduction of nervous impulses in NaCl-deficient media.

Abstract: Since Overton's finding on muscle (1), examination on the effect of Na deficient media upon the nervous function has been a centre of interest (27). The blocking concentration, or the minimal concentration required for conduction, has been said to be 10-15% of that of the normal Ringer for nonmyelinated fibres of the Crustacean (4) and 0.011 M for myelinated fibres of the frog (5), which are almost coincident with that obtained for muscle by Overton (about 10%). However, no precise determination has been made with respect to fibres of different types or sizes, although it seems certain that different fibres react in different manners to NaCl-deficiency (6, 7). According to Crescitelli, B-fibres are most sensitive to lack of sodium; they are blocked earlier than A-fibres and many of C-fibres in one and the same NaCl-deficient fluid; further, there are some differences among fibres belonging to A-group itself. These facts suggest that not only fibre types but also individual fibres of each type resist to NaCl-deficiency in different grades. The present study aims to clarify this point and, at the same time, to carry out observations on some phenomena of conduction NaCl-deficient solutions.

The influence of anions on the activity of gustatory receptors.

Abstract: (1) The influence of various anions on activity of gustatory receptors was investigated by adapting the tongue of a frog to modified anion-Ringer, in which all Cl was substituted for Br, I, NO3, SCN, SO4 and H2PO4.(2) Immediately after exchange of normal Ringer with one of these modified anion-Ringers the response of the tongue was not appreciably changed in its threshold to various taste solutions and in its magnitude.(3) 1-2 hours after exchange of the bathing medium the response of the tongue to salt solutions was reduced and its threshold was raised, while the threshold concentration of sodium salts to depress water response was raised. The sensitivity of the tongue to other kinds of taste stimuli was not very much modified compared with that to salts.(4) Sooner or later all the sensitivities of the tongue to various taste stimuliwere reduced or abolished.(5) The effects of anions mentioned above depended on the anions used; the effectiveness was in the order of SCN>NO3>I>Br. Sulphate had no marked effects on gustatory receptors, while their response was readily abolished in phosphate Ringer.(6) The sensitivity of the tongue was rapidly restored when the phosphate Ringer immersing the tongue was replaced by normal Ringer, whereas the effect of other monovalent anions was irreversible.(7) The following hypothesis was presented on the mechanism of salt reception and of the depressing action of salts on water response: Entry of cations inside gustatory receptor from the exterior is the initial step for the initiation of salt receptor activity and withdrawal of the intracellular potassium ions may initiate water response, which is prevented by exsistence of a sufficient amount of cations permeable to the membrane outside the cell. Anions reduce the permeability of the membrane to cations in the order of SCN>NO3>I>Br> Cl, or alternatively the cellular potassium reduces in the presence of SCN, NO3, Ior Br.

An application of a new method for recording the action potential of the single myelinated nerve fiber to detecting the cobalt-ion effect.

Abstract: The action potential of the single myelinated nerve fiber has been heretofore recorded as a current flow along the longitudinal axis of the fiber, using the so-called Tasaki's bridge insulator method. In this method a great magnification of the amplifier is required as the current thus led is extremely small. Stampfli (1), Tasaki and Frank (2) devised a new recording method capable of obtaining a height of the spike as great as that obtained by the intracellular recording technique. Their method is the same in principle as the intracellular microelectrode technique. The use of the intracellular microelectrode was proved not always suitable by several authors (3, 4, 5), since the impairement by the insertion of the electrode into such a small fiber is great. The authors adopted a new method of recording the action potential extracellularly using the pre-amplifier made for the intracellular microelectrode. The new method enables us to record the potential as great as the source of the action potential itself. It was .found that some heavy-metal ions have specific action on the node of Ranvier. In this paper the abnormal prolongation of action potential of the single myelinated nerve fibers of toad and heavy-metal ion effects on them is mainly dealt with.

Microspectrophotometric studies on desoxyribonucleic acid of an individual nucleus in the ox retina

Abstract: The chemical difference in the nuclei distributed in three nuclear layers was estimated by the microspectrophotometric method on the basis of the DNA content of an individual nucleus.The specificities in the extinctions were observed in the receptor nuclei, which showed the highest value compared to that of others.In order to obtain the relative content of DNA in the irregular nucleus containing a dense chromatin, the integral formula was applied. The constancy relation of the DNA content seemed to exist in the nuclei distributed in the identical nuclear layer.

The site of electron transfer to various acceptors in succinoxidase system, with special reference to that of ethylurethane

Abstract: A study of succinoxidase system in rat liver mitochondria has been made, with special reference to the site of action of ethylurethane, and the site of electron transfer to several electron acceptors in this system.1. The inhibitory action of ethylurethane on succinoxidase system varied with the variety of acceptors used and it was not observed when brilliant cresyl blue was the acceptor. The inhibition was completely reversible up to the concentration of 0.5 M.2. The existence of two pathways: an “antimycin A-sensitive” and an “antimycin A-resistant, ” was indicated to link ferricyanide, 2, 6-dichlorophenolindophenol, and methylene blue with the succinoxidase system. One of the factors involved in the antimycin A-sensitive pathway is cytochrome c.3. The sensitivity of succinoxidase toward ethylurethane was exaggerated by the treatment with antimycin A and BAL and by the addition of cytochrome c. On the other hand, simultaneous addition of ethylurethane failed to protect the inhibition by BAL. Antimycin A titer of succinoxidase was decreased slightly by the presence of ethylurethane.4. From these results, the mechanism of action of ethylurethane was discussed together with that of antimycin A and BAL, and it was concluded that the site of action of ethylurethane lies at the portion of cytochrome b and Slater factor.

Acetylcholine-hydrolyzing enzyme in the isolated inner and outer segments of the receptor cell of frog retina.

Abstract: 1) The activity of acetylcholine-hydrolizing enzyme was found to predominate in the inner segment compared with the outer segment of the receptor cell. These results may suggest the special function of the inner segment, in responce to the electrical or chemical reaction in the retina.2) The activity of aceylcholine-hydrolyzing enzyme was not affected by the light of a rather weak intensity.

Study on the influence of high hydrostatic pressure on solutions by the use of an improved stationary platinum electrode polarography

Abstract: Using an improved stationary platinum electrode polarography, current voltage curves of buffer and non-buffer solutions were compared under normal and various high hydrostatic pressures.(1) The effect of high pressure on various concentrated salt solutions is remarkable particularly in dilute solution as postulated by predecessors.(2) The pH of non-buffer solution undergoes change under high pressure probably owing to the quantity of dissociable weak electrolyte.(3) Pressure does not influence the buffer action of buffer solution.(4) Under high pressure it seems in general dissociation increases and reduction is liable to occur.

Unsteady rate of ATP hydrolysis by myosin and actomyosin in its initial phase.

Abstract: 1. The time course of ATP hydrolysis by myosin, H-meromyosin, myosin B and synthetic actomyosin was followed. The rate of ATP hydrolysis in the initial phase was unsteady, and was grater than that of ATP hydrolysis in the steady state.2. This phenomenon was due to neither to the impurity in ATP sample, nor to the rapid liberation of orthophosphate bound to myosin by the addition of ATP.3. The time needed to get into the steady state was shortened by the addition of Mg++ and was elongated by the addition of Ca++, of pyrophosphate and of EDTA.4. The magnitude of Michaelis constant in the initial phase was different from that of Michaelis constant in the steady state.5. The cause of this phenomenon was discussed.

The mechanism of interaction between two electron acceptors (relay effect) in succinoxidase system.

Abstract: It is well known that an oxidation-reduction system having lower standard redox potential, E'0, is able to reduce another system of higher E'0 and that the reduction actually takes place with a measurable rate only when an appropriate potential difference exists between the systems (1, 2). Further, the works of Kubo and associates (3) revealed that the reduction rate of an oxidationreduction dye (A) by an adequate reducing system is enormously increased by the addition of another suitable redox dye (B) of lower E'0 than that of A. Since B seems to behave as an intermediate electron carrier between A and the reducing system, they designated this phenomenon as "relay effect" and B was called as " relay dye". In a previous paper (4), it was shown that the reduction of ferricyanide (FECY) and 2, 6-dichlorophenol-indophenol (DCPP) by succinoxidase system (SOS), in the presence of cyanide, was markedly activated by the addition of cytochrome c (CYT. C), and that the activation was completely abolished by antimycin A. These results clearly indicates that CYT. C acts as a relay dye in the reduction of FECY and DCPP. From the view point of thermodynamics, however, it is incomprehensible that CYT. C(E'0=0.255 V) is included in an electron transport pathway to DCPP (E'0=0.189 V ). Similar phenomenon was previously pointed out by Kamakura (5), who found that the reduction of indigotetrasulfonate (E'0=-0.046V) by glucose dehydrogenase is significantly accelerated by the addition of methylene blue (MB) (E'0=0.011 V), but the mechanism of this reaction is still a matter of speculation. An attempt is made, therefore, in this article to describe the sequence of reduction when two acceptors coexist with a reducing system and to elucidate the nature of relay effect.