Affiliation:
1. Anesthesia Research Center and Division of Bioengineering, University of Washington Seattle, Washington 98105
Abstract
The use of maximum velocity of shortening (V
max
) as an index of contractility has been based on the assumption that V
max
of muscle fibers is equivalent to V
max
of the contractile element. It is shown here that such equivalence applies to the two-element model of skeletal muscle but not to three-element models of cardiac muscle. Analysis of published data in terms of the Voigt and Maxwell three-element models shows that the V
max
of the contractile element, unlike that of the muscle fibers, is not independent of fiber length but increases at least 50% for a 25% increase of fiber length. Moreover, V
max
of the contractile element is seen to be even more highly dependent on fiber length when correction is made for the nonuniform contribution of levels of active state to the force-velocity curves giving rise to V
max
of the contractile element.
It appears that in cardiac muscle an inotropic shift of V
max
of the contractile element cannot be distinguished from a shift due to change in fiber length, thus invalidating it as an index of contractility.
Publisher
Ovid Technologies (Wolters Kluwer Health)
Subject
Cardiology and Cardiovascular Medicine,Physiology
Cited by
184 articles.
订阅此论文施引文献
订阅此论文施引文献，注册后可以免费订阅5篇论文的施引文献，订阅后可以查看论文全部施引文献