Radioautography has been used to localize 45Ca in isotopically labeled frog skeletal muscle fibers which had been quickly frozen during a maintained tetanus, a declining tetanus, or during the period immediately following a tetanus or a contracture. During a tetanus almost all of the myofibrillar 45Ca is localized in the region of the sarcomere occupied by the thin filaments. The amount varies with the tension being developed by the muscle. The movement of calcium within the reticulum from the tubular portion to the terminal cisternae during the posttetanic period has a half-time of about 9 sec at room temperature and a Q10 of about 1.7. Repolarization is not necessary for this movement. Evidence is given to support the notion that most calcium efflux from the cell occurs from the terminal cisternae into the transverse tubules.
Article|
January 01 1970
The Intracellular Site of Calcium Activation of Contraction in Frog Skeletal Muscle
Saul Winegrad
Saul Winegrad
From the Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia 19104
Search for other works by this author on:
Saul Winegrad
From the Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia 19104
Received:
June 23 1969
Online ISSN: 1540-7748
Print ISSN: 0022-1295
Copyright © 1970 by The Rockefeller University Press
1970
J Gen Physiol (1970) 55 (1): 77–88.
Article history
Received:
June 23 1969
Citation
Saul Winegrad; The Intracellular Site of Calcium Activation of Contraction in Frog Skeletal Muscle . J Gen Physiol 1 January 1970; 55 (1): 77–88. doi: https://doi.org/10.1085/jgp.55.1.77
Download citation file: