[Postsynaptic potentiation of miniature currents of muscle fiber endplates in the rat diaphragm. The effect of an acetylcholinesterase inhibitor, temperature and curare].
Miniature end-plate currents (MEPC) were recorded in voltage-clamped end-plates of the rat diaphragm. A positive correlation between the amplitude and half-decay time of individual MEPC was found in control, after acetylcholinesterase (AChE) inhibition the correlation increased: correlation coefficients--0.29 and 0.49, respectively (28 degrees C). Addition of curare after the AChE inhibition caused a decrease in the amplitude and duration of MEPC, but had no effect on the correlation between these parameters. Cooling down to 18 degrees C led to the essential reduction of this correlation in control as well as after the AChE inhibition. Effect of the prolongation of the half-decay time due to the AChE inhibition was more significant at 28 degrees C than at 18 degrees C. The Q10 value for duration of the rising MEPC phase (about 2) was less than that for the half-decay time (about 3). The role of factors determining the MEPC duration is discussed. The results are explained by the postsynaptic potentiation in terms of the cooperative action of agonists on cholinoreceptors and of peculiarities of the acetylcholine diffusion from the synaptic cleft.
Krivoĭ
I I
II
Seĭ
T P
TP
D000818:Animals; D002800:Cholinesterase Inhibitors / Q000494:pharmacology*; D003472:Curare / Q000494:pharmacology*; D003964:Diaphragm / Q000187:drug effects / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects; D008839:Microelectrodes; D009045:Motor Endplate / Q000187:drug effects / Q000502:physiology*; D009469:Neuromuscular Junction / Q000502:physiology*; D051381:Rats; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000502:physiology*; D013696:Temperature; D013997:Time Factors
D002800:Cholinesterase Inhibitors; D017981:Receptors, Neurotransmitter; D003472:Curare
Postsinapticheskaia potentsiatsiia miniatiurnykh tokov kontsevoĭ plastinki myshechnykh volokon diafragmy krysy. Vliianie ingibitora atsetilkholinesterazy, temperatury i kurare.