[The electrical and contractile responses during hyperbarism in the frog neuromuscular preparation].
The well-known phenomenon of incrementing muscular contraction intensity induced by an increased ambient pressure is still unclear (P. Regnard, 1891). This study was done in order to establish whether an increased contraction intensity is the result of enhanced effect of triggering stimuli in response to pressure elevation to 100 atm or a rise in muscle contraction intensity depends on other reasons. When studying the nerve stimulation electric response (muscle action potential, MAP) at increased pressure, the MAP amplitude significantly decreased about two-fold whereas the contraction intensity increased two-fold. The response duration was also elevated. Since electric stimulation was supramaximal in an intensity throughout the experiment the contraction-generating nervous impulse was sufficient for stimulating all the muscle fibers. No significant changes in other parameters of electric potentials occurring during neuromuscular transmission under pressure have been found which agrees with available neurophysiologic data. Thus, the causes responsible for an increased contraction intensity appear to depend on an altered muscle fiber contractility. This phenomenon provides the basis for understanding the changes in peripheric structures of the body and the periphery contribution to the genesis of hyperbaric nervous syndrome.
Revina
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SK
Plaksin
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D000818:Animals; D001274:Atmospheric Pressure; D004558:Electric Stimulation; D004576:Electromyography / Q000379:methods; D004594:Electrophysiology; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000502:physiology*; D009469:Neuromuscular Junction / Q000502:physiology*; D011896:Rana temporaria
Issledovanie élektricheskogo i sokratitel'nogo otvetov pri giperbarii v nervno-myshechnom preparate liagushki.