In frog fast skeletal muscle, we find a decline of twitch, tetanus, and maximum K and caffeine contracture tensions as tonicity of the bathing solution is increased. The decline of tension independent of the method of producing contraction indicates that the major effect of hypertonicity is directly on contractile tension probably because of the increased internal ionic strength. However, there is some apparent disruption of excitation-contraction (E-C) coupling in solutions made three times the normal tonicity (3T solutions) since: (a) in 3T solutions tetanic and K contracture tensions decline to zero from a value near the average maximum caffeine contracture tension at this tonicity (10% of 1T tetanic tension). At this time, caffeine contractures of 10% of 1T tetanic tension can be elicited; (b) once the K contracture tension has declined, elevated [Ca++]o, 19.8 mM, restores K contracture tension to 13% of 1T tetanic tension. This probable disruption is not caused by changes in mechanical threshold since in 2T solutions the mechanical threshold is shifted by 12 mv in the hyperpolarizing direction. This is consistent with neutralization of fixed negative charges on the inside of the membrane. The repriming curve is also shifted in the hyperpolarizing direction in 2T solutions. Shifts of the repriming curve coupled with membrane depolarizations in 3T solutions (about 20 mv) may produce loss of repriming ability at the resting potential and disruption of E-C coupling.
Skip Nav Destination
Article navigation
1 February 1970
Article|
February 01 1970
Some Effects of Hypertonic Solutions on Contraction and Excitation-Contraction Coupling in Frog Skeletal Muscles
A. M. Gordon,
A. M. Gordon
From the Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Washington 98105
Search for other works by this author on:
R. E. Godt
R. E. Godt
From the Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Washington 98105
Search for other works by this author on:
A. M. Gordon
From the Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Washington 98105
R. E. Godt
From the Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Washington 98105
Received:
July 16 1969
Online ISSN: 1540-7748
Print ISSN: 0022-1295
Copyright © 1970 by The Rockefeller University Press
1970
J Gen Physiol (1970) 55 (2): 254–275.
Article history
Received:
July 16 1969
Citation
A. M. Gordon, R. E. Godt; Some Effects of Hypertonic Solutions on Contraction and Excitation-Contraction Coupling in Frog Skeletal Muscles . J Gen Physiol 1 February 1970; 55 (2): 254–275. doi: https://doi.org/10.1085/jgp.55.2.254
Download citation file:
Sign in
Don't already have an account? Register
Client Account
You could not be signed in. Please check your email address / username and password and try again.
Could not validate captcha. Please try again.
Sign in via your Institution
Sign in via your InstitutionSuggested Content
Caffeine- and Potassium-Induced Contractures of Frog Striated Muscle Fibers in Hypertonic Solutions
J Gen Physiol (September,1966)
Tension in Isolated Frog Muscle Fibers Induced by Hypertonic Solutions
J Gen Physiol (February,1973)
Block of contracture in skinned frog skeletal muscle fibers by calcium antagonists.
J Gen Physiol (March,1989)
Email alerts
Advertisement