Single muscle fibers were exposed to solutions made hypertonic (approximately 460 milliosmols/kg water) by addition of either NaCl, glycerol, urea, acetamide, ethylene glycol, or propylene glycol. The changes in either the fiber twitch tension or the volume were measured. In the case of NaCl both fiber volume and twitch tension fall rapidly to 64 and 27% of the respective initial value. These two values were maintained for the duration of the exposure. In the case of the other substances, the fiber volume and twitch tension also decreased but in these cases the effect was transient and the fibers recovered their initial volume and twitch tension. The rate of recovery in the different hypertonic media increased in the order: glycerol < urea < ethylene glycol < propylene glycol < acetamide. In the cases of the last three substances, the initial twitch value was recovered in less than 5 min and even surpassed. However, on returning to normal Ringer the fibers' ability to twitch or to develop potassium contractures was lost. The return of the fibers to normal Ringer after exposure to these hypertonic solutions causes a transient swelling of the fibers. However, when fibers were swelled by exposure to hypotonic media, they did not lose their ability to twitch on return to the normal Ringer.
Article| November 01 1968
Volume and Twitch Tension Changes in Single Muscle Fibers in Hypertonic Solutions
From the Centro de Biofísica, Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Venezuela.
Dr. Caputo's present address is Department of Physiology, Duke University Medical Center, Durham, North Carolina 27706
Received: April 29 1968
Online Issn: 1540-7748
Print Issn: 0022-1295
Copyright © 1968 by The Rockefeller University Press
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Carlo Caputo; Volume and Twitch Tension Changes in Single Muscle Fibers in Hypertonic Solutions . J Gen Physiol 1 November 1968; 52 (5): 793–809. doi: https://doi.org/10.1085/jgp.52.5.793
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