The Journal of General Physiology, Vol 79, 437-452, Copyright © 1982 by The Rockefeller University Press
Rate-limiting steps in the tension development of freeze-glycerinated vascular smooth muscle
JW Peterson 3d
A method for "skinning" arterial smooth muscle is presented which yields
isometric tension development typically 60-80% of maximum physiological
tension in the presence of micromolar Ca++ and millimolar Mg-ATP, while
retaining essentially the native protein content. Using the methods of "CA
jump," the time-course of Ca++-activated tension development in the skinned
artery can be made identical to, but not faster than, the rate of tension
development in the intact artery. In the skinned artery, activating free
[Ca++] does not substantially alter the rate at which tension development
approaches the final steady tension attained at that free [Ca++] (less than
25% decline in speed for a 10-fold decrease in [Ca++]). These observations
are taken to mean that the rate-limiting step in isometric tension
development in arterial smooth muscle does not depend directly on Ca++.