Isolation and contractile responses of single pregnant rat myometrial cells in short-term primary culture and the effects of pharmacological and electrical stimuli.

A modified method for enzymatically isolating myometrial cells from the pregnant rat has been developed and the mechanical properties of single cells in short-term primary culture have been studied in response to various stimuli. The dissociation method produced a high proportion of fully relaxed cells and these cells shortened and subsequently relaxed completely in response to successive applications of acetylcholine, angiotensin II, high K+ solution or depolarizing current. In single cells, the contractions induced by acetylcholine and high K+ solution were concentration-dependent. Maximal contractions were obtained with 135.6 mM K+ and 5 X 10(-4)M acetylcholine. In single myometrial cells, the time course of contractions induced by acetylcholine, high K+ solution or depolarizing current was similar, suggesting that the rate of shortening was determined by limits of the contractile mechanism. Scanning electron microscopy revealed a smooth surface to the relaxed cells which contrasted with the numerous evaginations present on fully contracted cells. These results demonstrate the retention of structural integrity, acetylcholine and angiotensin II receptors, and potential-dependent Ca channels in myometrial single cells in short-term primary culture. Cells produced by this technique may provide a useful model for detailed electrophysiological studies.