Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published March 1978 | public
Journal Article

Role of voltage-sensitive receptors in nicotinic transmission

Abstract

This paper compares the conductance induced by bath-applied acetyl-choline (ACh) and by the same transmitter released from nerve terminals at Electrophorus electroplaques. For the former case, dose-response relations are characterized by the maximal agonist-induced conductance, rγ (130 mmho/cm²), and by the concentration which induces half this conductance; this concentration is termed K_(app) and equals 50 micron at -85 mV. For the latter case, neurally evoked postsynaptic currents (PSCs) are characterized by the peak conductance during strongly facilitated release, g_(PSC), and by the rate constant for decay, α. Since g_(PSC) roughly equals rγ, it is concluded that the PSC activates nearly all available receptor channels. These and other data agree with recent estimates that during the growth phase of the quantal response, (a) the ACh concentration is at least several hundred micromolar; and (b) most nearby channels are activated. However both α and K_(app) increase during depolarization, at a rate of about e-fold per 86 mV. These observations on voltage sensitivity suggest that a suprathreshold synaptic event is rapidly terminated because the action potential abruptly releases ACh molecules from receptors.

Additional Information

© 1978 The Biophysical Society. Published by Elsevier Under an Elsevier user license. Received for publication 23 June 1977 and in revised form 10 November 1977. We thank D. Williams for assistance with the animals and dissections, and P. Hartig, J. Heuser, M. Salpeter, and R. Zucker for helpful discussion. This work was supported by National Institutes of Health grant NS-11756; by a Grant-in-Aid from the Muscular Dystrophy Association, Inc.; by a Muscular Dystrophy Fellowship to D.D.K.; by an Alfred P. Sloan Fellowship and NIH Career Development Award NS272 to H.A.L.; and by a Spencer Foundation Fellowship to R.E.S.

Additional details

Created:
August 19, 2023
Modified:
October 20, 2023