Smooth muscle contractility. Effects of hypoxia.

Mechanical perturbation of smooth muscle provides information about the mechanical properties of its crossbridges. We have developed a method for identifying: (1) that normally cycling and very slowly cycling are sequentially activated, (2) the moment of this transition, and (3) the proportions of the two types of bridges recruited. Hypoxia decreases muscle shortening ability before isometric force. The former is due to depression of activity of both types of bridges.