EXPRESSION OF DIFFERENT POTASSIUM CHANNELS IN CELLS ISOLATED FROM HUMAN MYOMETRIUM AND LEIOMYOMAS

OBJECTIVE: 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. STUDY DESIGN: Voltage-activated potassium currents were recorded by whole-cell patch-clamp techniques and analyzed for differences in expression, voltage-dependence, kinetics, and inactivation. RESULTS: 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. CONCLUSION: Different potassium channel currents, noninactivating and inactivating, are predominantly expressed in cells isolated from human myometrium and leiomyomas, respectively.