Ryanodine interferes with charge movement repriming in amphibian skeletal muscle fibers.
Cut twitch muscle fibers mounted in a triple Vaseline-gap chamber were used to study the effects of ryanodine on intramembranous charge movement, and in particular on the repriming of charge 1. Charge 1 repriming was measured either under steady-state conditions or by using a pulse protocol designed to study the time course of repriming. This protocol consisted of repolarizing the fibers to -100 mV from a holding potential of 0 mV, and then measuring the reprimed charge moving in the potential range between -40 and +20 mV. Ryanodine at a high concentration (100 microM) did not affect the maximum amount of movable charge 1 and charge 2, or their voltage dependence. This indicates that the alkaloid does not interact with the voltage sensor molecules. However, ryanodine did reduce the amount of reprimed charge 1 by approximately 60% suggesting the possibility of a retrograde interaction between ryanodine receptors and voltage sensors.
Gonzalez
A
A
Laboratorio de Biofisica del Musculo, Instituto Venezolano de Investigaciones Cientificas, Caracas, Venezuela.
Caputo
C
C
D000818:Animals; D001001:Anura; D055592:Biophysical Phenomena; D001703:Biophysics; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D007700:Kinetics; D008564:Membrane Potentials; D009124:Muscle Proteins / Q000187:drug effects / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism*; D012433:Ryanodine / Q000008:administration & dosage / Q000494:pharmacology*; D019837:Ryanodine Receptor Calcium Release Channel
D015220:Calcium Channels; D009124:Muscle Proteins; D019837:Ryanodine Receptor Calcium Release Channel; D012433:Ryanodine