[Variations in the sensitivity of the neuromuscular junctions of the frog to the blocking action of hyperkalemic solutions].
The depression of evoked transmitter release with solutions with enhanced (up to 8 mM) potassium concentration was studied in cut and voltage-clamped muscle fibers of frog m. cutaneous pectoris. As potassium blockade proceeds, a reduction of the second end-plate current to paired stimuli occurs before a change in the first end-plate current, the reduction of end-plate currents being simultaneous with the latency increase. The existence of variable sensitivity of different end-plates to potassium blocking action depends on year season and ionic environment. Possible mechanisms of potassium blocking action are discussed.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D003864:Depression, Chemical; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D009045:Motor Endplate / Q000187:drug effects; D009469:Neuromuscular Junction / Q000187:drug effects*; D011188:Potassium / Q000494:pharmacology*; D011896:Rana temporaria; D012621:Seasons; D009435:Synaptic Transmission / Q000187:drug effects*
D008274:Magnesium; D011188:Potassium; D002118:Calcium
Variiatsii chuvstvitel'nosti nervno-myshechnykh soedineniĭ liagushek k blokiruiushchemu deĭstviiu giperkalievykh rastvorov.