Effect of aramine-induced smooth muscle contraction on length-tension diagrams of venous strips.

The elastic properties of helically cut strips of peripheral veins of clogs were studied. Length-tension diagrams of relaxed venous strips are compared with those obtained when the smooth muscle of the strip is contracted in the presence of a long-acting sympathomimetic agent, Aramine. Sustained strong, muscular contraction is always associated with a change in the shape of the length-tension curve and a marked decrease in the extensibility of the tissue. The contribution to total strip tension of the smooth muscle relative to that of other tissue elements appears to be greater in this preparation than it is in certain previously described arterial tissues. Aramine causes smooth muscle contraction of the isolated vein strip in concentrations comparable to those probably achieved in vivo. This fact supports the hypothesis that Aramine can alter the pressure-volume characteristics of the venous bed in intact animals.