Gating kinetics of nonjunctional acetylcholine receptor channels in developing Xenopus muscle.
The development of nonjunctional acetylcholine (ACh) receptor gating kinetics was studied in myotomal muscle of Xenopus laevis by spectral analysis of ACh-induced noise. The results are consistent with the idea that there is a developmental shift in relative numbers of receptors with fast and slow gating kinetics. For about the first 20 hr following the onset of ACh sensitivity, the majority of channel openings contributing to the ACh noise were slow, having an apparent mean open time of about 3 msec. Shortly before the time of hatching, there began to appear a significant contribution to the noise from channels having a mean open time of less than 1 msec. The relative amount of fast channel activity increased during the 2 days following hatching, and by the age of maturity of the myotomal synapse, most of the ACh noise arose from fast channel activity. A comparison of nonjunctional kinetics with synaptic currents at maturity suggests that the control of channel gating time is similar at junctional and nonjunctional regions.
Kullberg
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R
Kasprzak
H
H
D000818:Animals; D004560:Electricity; D004594:Electrophysiology; D004625:Embryo, Nonmammalian; D007473:Ion Channels / Q000378:metabolism*; D007700:Kinetics; D007814:Larva; D024510:Muscle Development; D009132:Muscles / Q000378:metabolism; D011950:Receptors, Cholinergic / Q000378:metabolism*; D013223:Statistics as Topic; D014982:Xenopus laevis
D007473:Ion Channels; D011950:Receptors, Cholinergic