Potassium-induced contractures were studied in single fibers from the semitendinosus muscle of Rana pipiens. Contractures elicited by solutions containing 60–117 mM potassium and 120 mM chloride were biphasic, consisting of a rapid initial contraction with a duration at 23°C of less than 1 sec followed by a slow response with a duration of many seconds. At 13°C, the initial response was greatly prolonged so that the two responses virtually fused into a single smooth contracture. Membrane potential in high potassium, high chloride solutions underwent a transient peak depolarization, probably as a result of time-dependent changes in membrane conductance during depolarization. It is proposed that this complex time course of depolarization gives rise to the biphasic contracture response.
Article|
August 01 1971
Biphasic Potassium Contractures in Frog Muscle Fibers
L. L. Costantin
L. L. Costantin
From the Department of Physiology, College of Physicians and Surgeons, Columbia University, New York 10032
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L. L. Costantin
From the Department of Physiology, College of Physicians and Surgeons, Columbia University, New York 10032
Received:
March 25 1971
Online ISSN: 1540-7748
Print ISSN: 0022-1295
Copyright © 1971 by The Rockefeller University Press
1971
J Gen Physiol (1971) 58 (2): 117–130.
Article history
Received:
March 25 1971
Citation
L. L. Costantin; Biphasic Potassium Contractures in Frog Muscle Fibers . J Gen Physiol 1 August 1971; 58 (2): 117–130. doi: https://doi.org/10.1085/jgp.58.2.117
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