[Effect of changes in membrane potential and temperature on the post-synaptic potential on the neuromuscular junction of the frog].
The decay time-constants of the 2nd and 1st nerve-evoked paired end-plate currents (epc) were recorded in transversely cut muscle preparations of frog. After the inhibition of synaptic acetylcholinesterase by prostigmine (3 X 10(-6) mol/l) the decay of the 2nd epc was 39 +/- 8% slower than the decay of the 1st epc (the interstimulus interval being 100 ms) due to postsynaptic potentiation (PSP). It was found that PSP does not depend on the membrane potential level in the range of-30-120 mV. A drop in temperature from 22 degrees to 12 degrees resulted in several effects: an increase in the decay time constant of epc and meps; a slight decrease in mepc amplitude; a fall of epc quantal content. The comparison of paired epc of equal quantal content showed that PSP was more pronounced at lower temperature. The temperature coefficient (Q10) for the ratio of decay time constants of the 2nd and the 1st epc was 2.0 +/- 0.2. Evidently, the trace of preceding activity of the transmitter does not depend on the membrane potential level but becomes stronger with a fall of the temperature.
D000110:Acetylcholinesterase / Q000502:physiology; D000818:Animals; D008564:Membrane Potentials; D009045:Motor Endplate / Q000502:physiology; D009388:Neostigmine / Q000494:pharmacology; D009469:Neuromuscular Junction / Q000502:physiology*; D011896:Rana temporaria; D009435:Synaptic Transmission; D013696:Temperature
D009388:Neostigmine; D000110:Acetylcholinesterase
Vliianie izmenenii membrannogo potentsiala i temperatury na postsinapticheskuiu potentsiatsiiu v nervno-myshechnom soedinenii liagushki.