Showing papers in "Acta Physiologica Scandinavica in 1977"

Time course of changes in human skeletal muscle succinate dehydrogenase and cytochrome oxidase activities and maximal oxygen uptake with physical activity and inactivity.

Abstract: Succinate dehydrogenase (SDH) and cytochrome oxidase activities in the lateral vastus of the human quadriceps femoris muscle together with total body VO2 max were followed during an 8-10 week period of endurance training (n = 13) and a successive 6 week period without training (n = 8). During the training period there was a gradual increase in both VO2 max and muscle oxidative enzyme activities, all being significantly different from the pre-training levels after 3 weeks of training. After 8 weeks of training VO2 max was 19%, vastus lateralis SDH 32%, and cytochrome oxidase activity 35% above the pre-training levels respectively. 6 weeks post training VO2 max was still 16% above the pre-training level, and not significantly different from the level at the end of training (p greater than 0.2). In contrast vastus lateralis SDH activity had returned to the pre-training level. Cytochrome oxidase activity had returned to the pre-training level within two weeks post-training. The significantly faster post-training decline in skeletal muscle oxidative enzyme activities in contrast to that of the VO2 max indicates that an enhancement of the oxidative potential in skeletal muscle is not a necessity for a high VO2 max. Moreover, the fast return to the pre-training level of both SDH and cytochrome oxidase activities indicate a high turnover rate of enzymes in the TCA cycle as well as the respiratory chain.

Muscle adaptation to extreme endurance training in man.

Abstract: To evaluate the effect of extreme endurance training on muscle fibre composition and activities of oxidative enzymes in different fibre types biopsies were taken from vastus lateralis, gastrocnemius and deltoideus of elite orienteers. Comparisons were made between the (trained) leg muscles and the (relatively untrained) arm muscles, and with leg muscles of 16--18 years old boys. The orienteers had the same percentage type I fibres and vastus lateralis and gastrocnemius as in deltoideus, but higher percentage type I fibres in vastus lateralis compared with the controls. The similarity between trained and untrained muscle in the orienteers suggests that training had not caused the high percentage type I fibres which rather might be the result of selection of individuals with the best prerequisites for high oxidative capacity. However, the distribution of type II subgroups in the leg muscles of the orienteers differed from both their own deltoideus and leg muscles of the controls, the relationship IIA/IIB being altered in favour of the more oxidative IIA. The leg muscles of the orienteers also showed an increased occurrence of the normally IIC fibre. These latter findings point at the possibility of a training induced alteration in the subgroup pattern. Unlike in the controls there was no significant difference in succinate dehydrogenase activity, measured in single fibres, between type I and II fibres in gastrocnemius of the orienteers. Thus, type II fibres have the ability metabolically to adapt to high oxidative demands. This might to some extent be mediated by a conversion from IIB to IIA form. Language: en

Skeletal muscle fibres and muscle enzyme activities in monozygous and dizygous twins of both sexes.

Abstract: Significance of the genetic component in determining the interindividual variation observed in skeletal muscle fibre composition and enzyme activities was investigated in 31 pairs of male and female monozygous (MZ) and dizygous (DZ) twins, whose ages ranged in all but one pair (11 years) from 15 to 24 years. Percent distribution of slow twitch muscle fibres and activities of Ca2+ and Ng2+ stimulated ATPases, creatine phosphokinase, myokinase, phosphorylase, lactate dehydrogenase (LDH) and distribution of its isozyme LDH-1 were all analyzed in biopsy samples taken from the vastus lateralis muscle. The data disclosed that in contrast to DZ twins the MZ twins of both sexes had an essentially identical muscle fibre composition. Calculation of the heritability estimate for this parameter gave the values of 99.5% and 92.8%, respectively for males and females. In contrast to the fibre composition presence of a significant genetic component was not observed in any of the enzyme activities studied. It was concluded that there is a predominant genetic influence on the skeletal muscle fibre composition in man, and thus also on the potential capacity of the muscles to perform work.

Central and regional circulatory effects of adding arm exercise to leg exercise.

Abstract: 7 young, healthy, male subjects performed exercise on bicycle ergometers in two 20 min periods with an interval of 1 h. The first 10 min of each 20 min period consisted of arm exercise (38--62% of Vo2 max for arm exercise) or leg exercise (58--78% of Vo2 max for leg exercise). During the last 10 min the subjects performed combined arm and leg exercise (71--83% of Vo2 max for this type of exercise). The following variables were measured during each type of exercise: oxygen uptake, heart rate, mean arterial blood pressure, cardiac output, leg blood flow (only during leg exercise and combined exercise), arterio-venous concentration differences for O2 and lactate at the levels of the axillary and the external iliac vessels. Superimposing a sufficiently strenuous arm exercise (oxygen uptake for arm exercise greater than 40% of oxygen uptake for combined exercise) on leg exercise caused a reduction in blood flow and oxygen uptake in the exercising legs with unchanged mean arterial blood pressure. Superimposing leg exercise on arm exercise caused a decrease in mean arterial blood pressure and an increased axillary arterio-venous oxygen difference. These findings indicate that the oxygen supply to one large group of exercising muscles may be limited by vasoconstriction or by a fall in arterial pressure, when another large group of muscles is exercising simultaneously.

Changes in Motor Unit Activity and Metabolism in Human Skeletal Muscle during and after Repeated Eccentric and Concentric Contractions

Abstract: This study was designed to investigate electromyographic (EMG), muscle glycogen and blood lactate changes in quadriceps muscle group during repeated 40 maximal eccentric and concentric contractions, and to follow the recovery in EMG, muscle glycogen and serum creatine kinase values during a 4 day period following the work test. The subjects were normal males and the test order (eccentric or concentric) was randomly selected. The results indicated first, that the EMG parameters (IEMG, AMUP), muscle glycogen and blood lactate changed in a similar manner during the both fatigue loads. Despite the high tension work no selective depletion of glycogen could be observed in the slow or fast twitch muscle fibres in either type of work. The restoring of muscle glycogen occurred in a similar manner after the both fatigue loads, and no significant differences were present between eccentric and concentric works in the serum creatine kinase levels for a 2 days period. The eccentric work was associated with muscle soreness, which was strongest during the second day after the termination of the work test. The recovery of the EMG parameters were also delayed in eccentric fatigue. After concentric fatigue EMG-activity returned to normal values within 2 days.

Adrenergic and Cholinergic Nerves of the Human Urethra and Urinary Bladder. A histochemical study.

Abstract: The occurrence and distribution of adrenergic and acetylcholine esterase (AChE) positive nerves in the human urethra and urinary bladder were studied histochemically with the fluorescence method of Falck and Hillarp, and the copper thiocholine method of Koelle and Friedenwald. Both types of nerves were mainly confined to the layers of smooth muscle cells in the walls of the organs. In all parts of the urethra, there was a scanty supply of adrenergic nerves. Few adrenergic nerves were also found in the urinary bladder, except in the trigone area, where they were abundant. AChE-positive nerves were uniformly and richly distributed in the urinary bladder. Throughout the urethra the distribution of AChE-positive nerve fibres was uniform, but the number was clearly less than in the urinary bladder. No intramurally located adrenergic or AChE-positive ganglion cells could be demonstrated.

Extracellular Potassium Concentration in Juvenile and Adult Rat Brain Cortex during Anoxia

Abstract: The extracellular K concentration, ([K]e), in the brain cortex of rats at different ages was measured by means of K+-sensitive microelectrodes. [K]e was between 3 and 5 mM at all ages. Following nitrogen inhalation there was an increase in [K]e which exhibited a sigmoid pattern in every age group: Firstly, there was a slow rate of rise which was followed by a sudden, steep increase where the [K]e rose to about 70 mM. During the subsequent 5–10 min a plateau value of about 90 mM was reached. The prominent difference between the age groups was the time until the steep rise began. The time to the steep increase in [K]e and the [K]e at the start of the steep increase was inversely related to the age of the animal. A close relation was found between the time to the start of the steep increase and the time to the last gasp during nitrogen breathing (r - 0.98). It is suggested that the different resistence to anoxia in young and adult animals is related to differences in the ability to keep near normal potassium gradients across the cells in the brain.

Local reflex in microcirculation in human skeletal muscle.

Abstract: The effect of venous stasis of 40 mmHg upon blood flow in human skeletal muscle was studied in four normal subjects and in two chronically sympathectomized patients. Blood flow in skeletal muscle was measured by the local 133Xenon washout technique. Blood flow decreased about 30 per cent during venous stasis of 40 mmHg. In a "passive vascular bed" induced by means of histamine, blood flow decreased only by 16 per cent, indicating that the decrease in blood flow is due to a vasoconstrictor response to increase in vascular transmural pressure. The vasoconstrictor response was unaffected by a spinal sympathetic blockade, but was blocked in areas infiltrated with lidocaine or with phentolamine. The vasoconstrictor response was present in the nonoperated limbs used as a control, but abolished in the denervated arms in the two chronically sympathectomized patients. The findings strongly suggest that the vasoconstrictor response in skeletal muscle is due to a local nervous mechanism involving adrenergic fibres. Thus a local reflex mechanism, most likely a sympathetic axon reflex, seems to be present in human skeletal muscle as in cutaneous and subcutaneous tissue. This indicates that about 45 per cent of the change in total vascular conductance, when a person changes from supine to upright position, is due to this local reflex mechanism operating independently of the central nervous system.

Fatigue and EMG of Repeated Fast Voluntary Contractions in Man

Abstract: A fatigue test consisting of repeated fast maximal contractions of the left quadriceps muscle in an isokinetic apparatus was performed by 12 healthy male subjects (19-25 yrs). EMG signals recorded from the surface of the left vastus lateralis muscle, from which also biopsies were obtained for muscle fibre classification. Only minor changes were observed in the EMG variables despite a decrease in muscle strength performance, in terms of peak torque, work and power to about 50% of initial values after 100 contractions. The concomitantly obtained positive correlation between the increase in EMG/torque ratio and the individual percentage of fast twitch (FT) muscle fibres indicated that local factors in the muscle, primarily in FT fibres, were causing the development of fatigue during repeated dynamic contractions with high power outputs.

Flow and composition of leg lymph in normal men during venous stasis, muscular activity and local hyperthermia.

Abstract: Changes in normal human leg lymph protein concentration, output, and lymph flow/lymph protein concentration relationship, as well as lactate dehydrogenase and alkaline phosphatase activity were followed during procedures known to increase capillary filtration as venous stasis, muscular exercise and warming of tissues. Lymph flow increased by 83% during two hour ergometer cycling, and by 117% during two hour warm water foot bath. During a two hour period of venous stasis lymph flow dropped by 50%. There was an increase in lymph flow during the rest period following all three types of experiment, most pronounced after foot warming. An inverse relationship between the lymph flow rate and lymph protein concentration was found. Lymph enzymes followed the same pattern of changes as total protein.

Inhibition of Gastric and Intestinal Motor Activity in Dogs by (Gln4) Neurotensin

Abstract: The action of (Gln4)-neurotensin was studied on the spontaneous motor activity in isolated canine fundic, antral and intestinal pouches. All pouches had been prepared more than 6 months prior to the experiments. Spontaneous motor activity was recorded for at least 1 h before the Gln4)-neurotensin was infused i.v. for 30 min in doses ranging between 6.3 and 100 ng X kg-1 X min-1. In the vagally denervated fundic pouches (Gln4)-neurotensin inhibted motor activity in doses above 25 ng X kg-1 X min-1. The vagally innervated antral pouches were more sentitive than the vagally denervated fundic pouches to the action of (Gln4)-neurotensin. Thus motor inhibition was induced by doses as low as 6.3 ng X kg-1 X min-1. The effect of (Gln4)-neurotensin on motor activity in intestinal pouches was inconsistent. Inhibition was seen in 1 out of 7 expts. The present results show that the gastric motor activity is the most sensitive function to (Gln4)-neurotensin so far studied.

Comparative study of some isolated mammalian smooth muscle effectors of penile erection.

Abstract: Spontaneous rhythmic activity, responses to drugs and effects of field stimulation of nerves of the retractor penis (rp) and/or corpus cavernosum urethrae (ccu) of macaque, rabbit, guinea-pig, rat, dog, cat, horse, boar, elk, bull, ram and goat, as well as of the penile artery (pa) of bull were studied. A basic property of all these muscles was automaticity. Their responses to 5-hydroxytryptamine, histamine, adenosine triphosphate, prostaglandins E1, E2, AND F2alpha, oxytocin, vasopressin, substance P, bradykinin and angiotensin exhibited considerable species variations. Their excitatory innervation seems to be adrenergic. They also have an inhibitory innervation. In spite of comprehensive pharmacological analysis the inhibitory mediator remains obscure. The frequency--response relationship to inhibitory nerve stimulation was characterized by a rapidly achieved maximum at low frequencies, indicating high efficiency of the neuroeffector unit.

Regulation of the Heart of a Teleost, Gadus morhua, by Autonomic Nerves and Circulating Catecholamines

Abstract: The cod heart regulation has been investigated by anatomical studies, fluorescent histochemistry, nerve stimulation and drug effects on the perfused heart and electrically paced strips. The effect on the heart of catecholamine release from the head kidney has been studied in a perfused head kidney and heart preparation. Branches of the vagi and the fused 1st and 2nd spinal nerves innervate the heart. Specifically fluorescent fibres were found in these nerve branches, in the ducts of Cuvier, all parts of the heart, bulbus arteriosus and the ventral aorta. Weakly autofluorescent ganglion cells surrounded by specifically fluorescent varicose fibres were present in the walls of the sinus venosus. Vagal stimulation caused bradycardia altered after atropine to tachycardia. Spinal nerve and sympathetic chain stimulation also induced tachycardia, as did provoked catecholamine release from the head kidney. The tachycardia could be blocked by propranolol. Atropine increased and propranolol decreased basic heart rate and contraction force. Adrenergic drugs accelerated and acetylcholine retarded the perfused heart. A positive inotropic effect was obtained with adrenergic drugs on isolated heart strips, while acetylcholine produced a negative inotropic effect on atrial but not ventricular strips. It is concluded from this study that the cod heart has an inhibitory cholinergic nerve supply via the vagi and an excitatory adrenergic supply via both the vagi and the first spinal nerves. Sympathetically controlled release of catecholamines from the chromaffin tissue in the head kidney may also play an important role in the heart regulation.

Anaerobic performance capacity in athletes.

Abstract: Anaerobic performance characteristics of the whole body and at muscle tissue level were studied in 89 athletes and 31 reference subjects. The main parameters were vertical velocity during running up the stairs, maximal isometric force of leg extensor muscles, blood lactate concentration after maximal treadmill running test, percentage of fast twitch muscle fibers (% FT fibers), lactate dehydrogenase (LDH) and creatine phosphokinase (CPK) activity in vastus lateralis muscle. These parameters tended to divide the athletes and their sport events into neuromuscular, anaerobic and aerobic types. The specific needs of the different sport events might have masked the expected characteristics of energy and power utilization. However, a high percentage of FT fibers might be a prerequisite for a successful athlete in certain neuromuscular-anaerobic type events ("power events"). The main parameters describing the anaerobic performance capacity of the whole body (vertical velocity, leg force, blood lactate) were found to be related to muscle fiber composition (% FT fibers). The running velocity rather than muscle strength seemed to be more influenced by activity of enzymes LDH and CPK.

Protein concentration in interstitial and lymphatic fluids from the subcutaneous tissue.

Abstract: The protein content of interstitial fluid and lymph from the same tissue was determined fluid samples of nanolitre volumes being taken from the subcutaneous tissue of rabbits by micropuncture. In the same area lymph was collected from lymphatic vessels of 30-100 mum. An electrophoretic technique in polyacrylamide gels in glass capillaries was used for the analysis of proteins. The gels were stained and then scanned on a microscope equipped with a moving table and photomultiplier. The area under each protein band was calculated from the recorded densitograms. The method required only a few nanolitres of fluid for analysis. Using solutions of known protein concentrations the relationship between the amount of protein and the area under the densitogram band was investigated. This relationship was found to be linear, making it possible to quantify the protein content of both interstitial fluid and lymph samples. The interstitial fluid/plasma concentration ratios for albumin, transferrin, globulins and total proteins were 0.42, 0.42, 0.32 and 0.37. The albumin/globulin ratio in interstitial fluid was found to be 1.60 of the plasma value although the values obtained for lymph were similar to those found for interstitial fluid. The similarity between the protein concentration of interstitial fluid and lymph indicated that the endothelial lining of the terminal lymphatics did not restrict the passage of macromolecules into the lymphatics.

Skeletal muscle fiber splitting induced by weight-lifting exercise in cats.

Abstract: Adult skeletal muscle hypertrophy induced by exercise has been thought to be exclusively related to an increase in cross-section area of individual muscle fibers and not to an increase in the number of muscle fibers. Recent experiments using surgical intervention to cause muscle overload have induced an increase in fiber numbers; however, the muscle also exhibited pathological alterations. The purpose of this study was to determine if an exercise regimen also induced hyperplasia. Cats were trained to lift weights with their right forelimb to receive a food reward. After 19-46 weeks of training, the flexor carpi radialis muscle (FCR) was removed and prepared for histochemical examination. The total number of muscle fibers of the right exercised FCR increased significantly (19.3%) when compared with that of the unexercised left FCR (p less than 0.05). This increase was found to be due to muscle fiber splitting.

Effects of Prostaglandins on the Isolated Human Bladder and Urethra

Abstract: The effects of prostaglandins F2 alpha (PGF2 alpha), E1 (PGE1) and E2 (PGE2) on the human lower urinary tract were studied in vitro in preparations obtained from patients undergoing total cystourethrectomy because of bladder malignancy. Tissue specimens were taken from different parts of the urethra, the urethrovesical junction, and the bladder. From these specimens, smooth muscle preparations were dissected and mounted in organ baths, that were filled with Krebs solution (37 degrees C) and bubbled with carbogen. Isometric tension was recorded. Preparations from the bladder and all parts of the urethra were contracted by PGF2 alpha. This effect was not affected by tetrodotoxin, phenoxybenzamine, or atropine; isoprenaline relaxed the PGF2 alpha induced contractions. PGE1 and PGE1 both contracted strips from the bladder. However, urethral preparations contracted by PGF2 alpha or noradrenaline were relaxed by these agents. This relaxing effect was at least as pronounced as that produced by isoprenaline; it was not affected by propranolol.

Fever and behavioural temperature regulation in the frog Rana esculenta.

Abstract: The skin and colonic temperatures were recorded in frogs (Rana esculenta) which had selected a suitable microenvironment in a box filled with 2-3 cm water. The water temperatures ranged from 0 degrees C to + 40 degrees C. Such measurements were performed before and after intraperitoneal injections of killed pathogenic bacteria (M. xenopi and M. range), killed non-pathogenic bacteria (M. aquae II) and 0.9% sterile saline, intraperitoneal injections of blood plasma from frogs pre-injected with killed M. ranae, injections of PGE1 into the brain. The injections of pathogenic bacterial endotoxin caused, after latencies of 5-120 min, higher preferred water temperatures, which produced an average maximum colonic temperature increase of 6.5 degrees C +/- 1.0 degrees C (S.E.) (p less than 0.001). The non-pathogenic bacteria and sterile saline caused no temperature change. Monophasic hyperthermia of shorter latency was caused by injections of blood plasma from frog preinjected with M. ranae. Monophasic hyperthermia of the shortest latency was observed after diencephalic injections of PGE1. Based on their similarity we suggest that ectothermic and endothermic fever have a common phylogenetic origin.

Observations on the morphology at the transition between the peripheral and the central nervous system in the cat. IV. Unmyelinated fibres in S1 dorsal rootlets.

Abstract: Unmyelinated (d.r.C) fibres have been investigated electronmicroscopically at their passage from the peripheral to the central nervous system in feline S1 dorsal rootlets. The earlier demonstrated rearrangement of C-fibres during their passage along the transitional region (TR) was confirmed by the observation of extensive fibre divergence. The transitional region Schwann cells was calculated to be 10-20 times as high in the TR as in the more distal parts of the rootlets. Analysis of consecutive ultra-thin sections showed that PNS unmyelinated axons 0.8 micrometer or more acquired a myelin sheath as they entered the CNS. Fibres 0.6-0.8 micrometer in diameter appeared to be segmentally myelinated in the CNS. Fibres less than 0.6 micrometer remained unmyelinated at their CNS entrance. A few fibres showed degenerative signs and terminated in the transitional region.

Mechanical, electrical, and biochemical effects of hypoxia and substrate removal on spontaneously active vascular smooth muscle.

Abstract: Effects of hypoxia and glucose-free solution on the isolated rat portal vein were studied. Decrease of extracellular PO2 below 50 mm Hg caused graded inhibition of spontaneous mechanical activity; below 7 mm Hg, inhibition was complete in most preparations. Contracture force of depolarized portal vein was less sensitive to decreases in PO2. Responses to noradrenaline at all concentrations were markedly depressed at extreme hypoxia. Sucrose-gap experiments showed that hypoxia reduced the spontaneous electrical spike discharge. Mean tissue contents of PCr, ATP and glycogen (expressed as glucose) were 3.02, 2.47 and 5.07 micromol/g cell wt. in spontaneously active control muscles and 1.07, 1.65 and 1.83 after 20 min anoxia. Physiological variations in PO2 may influence myogenic activity of vascular smooth muscle largely through an action at the membrane level and this mechanism may participate in local blood flow control. Caculations indicated that the graded response to hypoxia in the present in vitro experiments was not due to diffusion limitation. Spontaneous mechanical activity was relatively well maintained even after prolonged exposure to glucose-free solution, whereas the responses to K+ and noradrenaline were markedly suppressed. Electrophysiological recordings during spontaneous activity indicated desynchronization and impaired conduction. PCr and ATP were maintained at control levels and glycogen reduced by 50 per cent after 2 h in glucose-free medium. Indications of the use of amino acids (glutamate) as substrate under these conditions were obtained.

K+-permeability of the blood-brain barrier, investigated by aid of a K+-sensitive microelectrode.

Abstract: The K+-permeability of the blood-brain barrier at the capillary level was estimated from determinations of brain extracellular K+-concentration in response to an isotonic bolus containing KCl injected into the carotid artery. A very low permeability appeared from the fact that the extracellular K+-concentration--measured by aid of K+-sensitive microelectrodes--remained unchanged during the passage of the bolus. An upper limit for the blood-brain barrier K+-permeability in the rat was estimated to be 2.8 X 10(-7) cm. with s-1.

Localization of Adrenergic Receptors in Guinea Pig Ileum and Rabbit Jejunum to Cholinergic Neurons and to Smooth Muscle Cells

Abstract: The localization of adrenergic receptors mediating a relaxing action was investigated in innervated and denervated longitudinal muscle strips from guinea pig ileum and rabbit jejunum. Denervated preparations were contracted by drugs that had a direct effect on smooth muscle cells, such as acetylcholine and histamine, but not by stimuli acting on cholinergic neurons, such as electrical field stimulation or nicotine. After blockade of beta-adrenoceptors, norepinephrine relaxed the innervated guinea pig ileum contracted by electrical field stimulation, by stimulating alpha-adrenoceptors. Norepinephrine in low concentrations did not relax denervated preparations contracted by agents acting directly on smooth muscle. In high concentrations, it relaxed denervated preparations by a nonadrenergic mechanism, resistant to alpha- and/or beta-receptor blockade, but which was also activated by 1-(3,4-dihydroxyphenyl) ethanol. Phenylephrine only had a weak agonistic effect on the electrically stimulated innervated preparation and did not relax the denervated one. The denervated rabbit intestine contracted by acetylcholine was relaxed by norepinephrine and phenylephrine by stimulation of alpha-adrenoceptors. In the innervated preparations both drugs were more effective in inhibiting contractions induced by electrical field stimulation or eserine than those induced by exogenous acetylcholine. Both the denervated guinea pig and rabbit intestine were relaxed by stimulation of beta-adrenoceptors. It is suggested that in the guinea pig ileum alpha-adrenoceptors mediating relaxation are located only in cholinergic neurons, whereas in rabbit jejunum they are located both in these neurons and in the smooth muscle cells. Beta-adrenoceptors are located in the smooth muscle cells of both organs.

Regulation of Salivary Kallikrein Secretion in the Rat Submandibular Gland

Abstract: Unstimulated pairs of rat submandibular glands were compared with regard to their wet weight, total protein content and kallikrein activity quantitated by Bz-Arg-OEt-esterase and kallikrein antigenic activity. Paired glands from the same animal were found to be comparable, whereas differences from one animal to another were considerable. One of two paired glands was extirpated and used as control, and the other was subsequently subjected to stimulation. Salivary secretion was induced parasympathomimetically (intraperitoneal injections of pilocarpine; perfusion with acetylcholine and electrical stimulation of the ductal nerve plexus near the gland hilus) or sympathomimetically (cervical sympathetic nerve stimulation with or without administration of α or β-adrenergic blocker; perfusion with epinephrine, norepinephrine or isoproterenol). The effect was studied by measuring the change in total gland kallikrein content and by quantitation of kallikrein in saliva. A small secretion of kallikrein was always observed. However, oc-adrenergic stimulation was 40 and 1500 fold more effective in releasing kallikrein than β-adrenergic and parasympathomimetic stimulation, respectively. Also, significantly more kallikrein was released by β-adrenergic than parasympathomimetic stimulation. Immunohistochemistry confirmed the observed depletion of kallikrein following α-adrenergic stimulation. No alteration in kallikrein localization was observed in stimulated glands.

Catecholamines and pancreatic hormones during autonomic blockade in exercising man.

Abstract: The importance of autonomic nervous activity for the pancreatic hormonal response to exercise in man was studied. 7 men ran at 58% of V(O2)max (determined without administration of drugs) to exhaustion during alpha-adrenergic blockade with phentolamine (P), during parasympathetic blockade with atropine (A), or without drugs (C). At rest phentolamine increased the plasma concentrations of both insulin and norepinephrine. During exercise norepinephrine concentrations increased and were in P experiments 3 times the concentrations in C experiments. Insulin always declined during exercise but in P experiments never decreased below basal levels. At identical times neither glucagon nor glucose differed significantly in the different expts. Thus during exercise alpha-adrenergic blockade increased insulin concentrations but did not diminish the glucagon response. Nor was this response increased when beta-receptor stimulation in P experiments was intensified by the particularly high catecholamine concentrations. The concentrations of FFA, glycerol and lactate were highest in P experiments and identical in A and C experiments. These findings indicate that during prolonged moderate exercise in man insulin secretion is depressed by stimulation of alpha-adrenergic receptors whereas glucagon secretion is not influenced by adrenergic receptors. Stimulation of beta-adrenergic receptors enhances lipolysis but neither lipolysis nor pancreatic hormonal secretion is influenced by cholinergic activity during exercise.