Myotonic responses produced by alteration of the function of ionic channels

It has been established that in sodium isethionate Ringer's solution containing chloride ions at low concentration (0-6.1 mmol/l) a repetitive firing of action potentials (APs) could be induced systematically by stimulation of muscle fibres with single square impulses. Repetitive firings occurred also on slow depolarization elicited by different agents e.g. by some antibiotics (primycin, desertomycin) which block potassium channels, or aldehydes (acrolein). On the basis of own and literary data it is concluded that under physiological conditions a high chloride concentration in the extracellular space prevents the occurrence of repetitive firing of APs which would result from the depolarization of tubular membrane on potassium ion accumulation in the luminal fluid of T-tubules.