The effect of temperature on charge movement repriming in amphibian
skeletal muscle fibers.
Gonzalez, Adom, and Carlo Caputo.
Laboratorio de Biofisica del Musculo, Centro de Biofisica y
Bioquimica, Instituto Venezolano de Investigaciones Cientificas, Ap
21827, Caracas 1020 A Venezuela
APStracts 2:0424C, 1995.
Cut twitch muscle fibers, mounted in a triple Vaseline-gap chamber,
were used to study the effects of temperature on intramembranous
charge movement, and in particular on the repriming of charge 1.
Changing the holding potential from -90 mV to 0 mV, modified the
voltage distribution of charge movement but not the maximum movable
charge. Temperature changes between 16 and 5 oC did not modify the
fiber linear capacitance, the maximum non-linear intramembranous
charge, or the voltage distribution of charge 1 and charge 2. We used
a pulse protocol designed to study the repriming time course of
charge 1, with little contamination from charge 2. The time course of
charge movement repriming at 15 oC is described by a double
exponential with time constants of 4.2 s and 25 s. Repriming kinetics
was found to be highly temperature dependent, with two rate limiting
steps with Q10 of 1.7 and 7.1 above and below 11.5 degrees C
respectively. This is characteristic of processes with high energy of
activation, and could be associated with a conformational change of
the voltage sensor or with the interaction between the voltage sensor
and the calcium release channel.
Received 17 November 1994; accepted in final form 1 September
1995.
APS Manuscript Number C676-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 December 95