Optical evidence for a chloride conductance in the T-system of frog skeletal muscle |
| |
Authors: | J. A. Heiny J. R. Valle S. H. Bryant |
| |
Affiliation: | (1) Department of Physiology and Biophysics, University of Cincinnati College of Medicine, 45267-0576 Cincinnati, OH, USA;(2) Department of Physiology and Pharmacology, University of San Luis Potosi School of Medicine, S.L.P., Mexico;(3) Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, 45267-0575 Cincinnati, OH, USA |
| |
Abstract: | T-system action potentials were recorded optically from intact frog skeletal muscle fibers stained with the non-penetrating potentiometric dye NK-2367. The effect of chloride removal on the falling phase of the radially propagating tubular action potential was studied to determine whether a chloride conductance located in the T-system membranes contributes to tubular repolarization during activity. Our results show that, in chloride-free Ringer, repolarization of the tubular action potential is significantly slowed. Moreover, the late phase of tubular repolarization is characterized by a large afterpotential, which is highly temperature-dependent and appears as a secondary peak above 10° C. The optical data were compared with predicted T-system action potentials generated from a radial cable equivalent circuit model of the T-system, in which the effects of a distributed tubular leak conductance were tested. Results of this analysis are consistent with the proposal that some of the outward repolarization current during the T-system action potential is drawn across a chloride conductance located in the T-system membranes. |
| |
Keywords: | Chloride conductance Skeletal muscle T-system |
本文献已被 SpringerLink 等数据库收录! |
|