Expression of different potassium channels in cells isolated from human myometrium and leiomyomas.

Abstract

Electrophysiologic characteristics of human myometrial and leiomyomatous cells isolated in culture were investigated. Both types of cell were shown to be smooth muscle cells by immunofluorescence. Voltage-activated potassium currents were recorded by whole-cell patch-clamp techniques and analyzed for differences in expression, voltage-dependence, kinetics, and inactivation. Depolarizing-voltage steps from -90 mV to +30 mV elicited two types of noninactivating outward currents that differed in their kinetics in 83% (n = 36) of normal cells in culture for 3 to 5 days; 6% responded with fast (3.5 milliseconds) outward inactivating currents; 11% in culture for 1 day responded only with long-lasting inactivating currents (33.2 +/- 7.2 milliseconds). Cells isolated from leiomyomas responded preferentially (65%, n = 31) with fast (3.3 +/- 0.1 milliseconds) outward inactivating currents; 35% responded with noninactivating outward currents similar to those from normal cells. Different potassium channel currents, noninactivating and inactivating, are predominantly expressed in cells isolated from human myometrium and leiomyomas, respectively.