The membrane of tissue-cultured chick pectoral muscle contains an ionic channel which is activated by membrane stretch. Nicotinic channels and Ca2+-activated K+ channels are not affected by stretch. In 150 mM-external K+ and 150 mM-internal Na+ the channel has a conductance of 70 pS, linear current-voltage relationship between -50 and -140 mV and a reversal potential of +30 mV. Kinetic analysis of single-channel records indicates that there are one open (O) and three closed (C) states. The data can be fitted by the reaction scheme: C1-C2-C3-O. Only the rate constant that governs the C1-C2 transition (k1,2) is stretch-sensitive. None of the rates are voltage-sensitive. The rate constant k1,2 varies with the square of the tension as k1, 2 = k0 X e alpha T2, where alpha is a constant describing the sensitivity to stretch and T is the tension. A typical value of alpha is 0.08 (dyn cm-1)-2. Following exposure to cytochalasin B the channel becomes more sensitive to stretch. The stretch-sensitivity constant, alpha, increases from 0.08 to 2.4 (dyn cm-1)-2. The probability of the channel being open is strongly dependent upon the extracellular K+ concentration. With a suction of 2 cmHg the probability increases from 0.004 in normal saline (5 mM-K+) to 0.26 in 150 mM-K+. The channel appears to gather force from a large area of membrane (greater than 3 X 10(5) A2), probably by a cytochalasin-resistant cytoskeletal network.

Stretch-activated single ion channel currents in tissue-cultured embryonic chick skeletal muscle.

Capsaicin-sensitive sensory neurons convey to the central nervous system signals (chemical and physical) arising from viscera and the skin which activate a variety of visceromotor and neuroendocrine reflexes integrated at various levels (intramurally in peripheral organs, at level of prevertebral ganglia, spinal and supraspinal level). Much evidence is now available that peripheral terminals of certain sensory neurons, widely distributed in skin and viscera have the ability to release, upon adequate stimulation, their transmitter content. In addition to the well-known "axon reflex" arrangement, the capsaicin-sensitive sensory neurons have the ability to release the stored transmitter also from the same terminal which is excited by the environmental stimulus. The efferent function of these sensory neurons is realized through the direct and indirect (i.e. mediated by activation of other cells) effects of released mediators. The action of released transmitters on postjunctional elements covers a wide range of effects which may have a physiological or pathological relevance. Development of drugs capable of controlling the sensory-efferent functions of the capsaicin-sensitive sensory neurons represent a new and very promising area of research for pharmacological treatment of various human diseases.

The sensory-efferent function of capsaicin-sensitive sensory neurons

Cortical cellular phenomena in experimental epilepsy: interictal manifestations.

Hair cells, the primary receptors of the auditory, vestibular, and lateral-line sensory systems, produce electrical signals in response to mechanical stimulation of their apical hair bundles. We employed an in vitro preparation and intracellular recording to investigate the transduction mechanism of hair cells in the sacculus from the inner ear of the bullfrog (Rana catesbeiana). When stimulated directly by mechanical deflection of their hair bundles, these cells gave graded responses up to 15 mV in amplitude; the peak sensitivity was about 20 mV/micron deflection. The depolarizing component of the receptor potential corresponding to stimuli directed towards the kinocilium. Depolarizing responses were associated with a membrane resistance decrease, and hyperpolarizing responses with a resistance increase. Action potentials, possibly calcium spikes, were occasionally evoked in hair cells by mechanical or electrical stimulation.

https://www.pnas.org/content/pnas/74/6/2407.full.pdf

Sensitivity, polarity, and conductance change in the response of vertebrate hair cells to controlled mechanical stimuli

Although information from sense organs is used by all animals, only man can verbally report his sensory experience. A brief consideration of these experiences may be useful in providing insight into cutaneous sensory mechanisms. Nonnoxious deformation of the human skin with a stimulator having a small surface area (2–3 mm2) evokes sensations usually referred to as “touch”. If the stimulator remains stationary, the sensation fades. Movement of the stimulator perpendicular to the skin produces changes in the sensory process which allow even rapidly repeated stimuli (e.g. 500 Hz) to be distinguished from stationary ones. When larger stimulators are used, some appreciation of texture can be obtained, and this is enhanced by movement of the stimulating surface across the skin. A smooth stimulator or an insect moving slowly and gently over the skin evokes distinctive sensations usually referred to as “tickle”. A sharp object such as a pin lightly pressed against certain points in the skin leads to an unpleasant experience which differs from touch but is equivocally painful; when the pin is pressed against the skin more firmly it usually elicits pain. Thus, sensations induced by mechanical events can be diverse. Moreover, common experience indicates that they may occur with greater or lesser intensity. On the other hand, neurophysiological experiments defining the properties of cutaneous sense organs have most often been done on animals other than man.

Cutaneous Mechanoreceptors and Nociceptors

Relation between stimulus strength, generator potential and impulse frequency in stretch receptor of Crustacea.

New evidence is presented that spike and transducer processes in sensory receptors are independent events; impulse activity in tile crustacean stretch receptor neuron and the mammalian pacinian corpuscle was selectively blocked by a compound (tetrodotoxin) without affecting any of the parameters of the generator potential.

https://science.sciencemag.org/content/sci/142/3596/1180.full.pdf

Separation of Transducer and Impulse-Generating Processes in Sensory Receptors

The effect of changes of the ionic environment upon an isolated crustacean sensory neuron.

The effect of strychnine upon the electrical activity recorded from the axon and the soma of an isolated nerve cell (the nonadapting stretch receptor cell of the crayfish) was studied. Protracted exposure of the soma of the cell to strychnine prolongs the duration of the intracellulary recorded action potential, as has been described in other excitable tissues treated with quaternary ammonium ions. During the plateau in the falling phase of the soma spike, the axon is usually firing repetitively. The stimulation of the inhibitory fiber produces a premature termination of the prolonged spike.

https://science.sciencemag.org/content/sci/133/3449/333.full.pdf

Yoshiaki Washizu

Papers

Relation between stimulus strength, generator potential and impulse frequency in stretch receptor of Crustacea.

Separation of Transducer and Impulse-Generating Processes in Sensory Receptors

The effect of changes of the ionic environment upon an isolated crustacean sensory neuron.

Effect of Strychnine upon the Electrical Activity of an Isolated Nerve Cell