Augmentation by calmodulin of Ca2+-induced tension development in saponin-treated (chemically skinned) rat uterine smooth muscle fibers

Abstract
The effect of calmodulin, an intracellular Ca2+ receptive protein, on tension development in saponin-treated (chemically skinned) uterine smooth muscle fibers of nonpregnant mature rats is described. The tension induced by Ca2+ was augmented by calmodulin in a dose-dependent manner at the fixed free Ca2+ concentration (pCa), and this augmentation was much greater at high Ca2+ concentrations (pCa < 5) than at low Ca2+ concentrations (pCa > 5). Free calmodulin in rat uterine smooth muscle cells may play some role in controlling tension development through interaction with intracellular free Ca2+.