The effect of calcium on the desensitization of membrane receptors at the neuromuscular junction.

摘要: Desensitization, as represented by the progressive decline in electromotive effects of depolarizing agents at neuromuscular junction, was studied observing time course changes effective transmembrane resistance during prolonged application 0.27 mM carbamylcholine to postjunctional region frog skeletal muscle fibers. The measured means two intracellular microelectrodes implanted junctional single When applied there an immediate decrease membrane followed a slower return toward control values which identified phase desensitization. calcium concentration increased from 0 10 approximately sevenfold increase rate On other hand, sodium 28 120 caused slowing Even muscles depolarized potassium sulfate, desensitization while high concentrations tended prolong process. Some mechanisms might exert these are discussed.