LUTEINIZING-HORMONE ACTIVATES CHLORIDE CURRENTS IN HEN OVARIAN GRANULOSA-CELLS

Luteinizing hormone (LH) induces progesterone production in hen ovaria n granulosa cells, and this induction is inhibited when chloride ions are removed from the culture medium. This suggests that chloride chann els may be involved in the signal transduction pathway responsible for the LH-induced progesterone production. In this report, we examined e ffects of LH on plasma membrane ion currents in single granulosa cells isolated from the largest preovulatory follicle (F-1) of the hen (Gal lus domesticus). Using the perforated patch whole cell voltage clamp t echnique, we found that addition of LH rapidly activated a chloride cu rrent in these cells. This chloride current was present at all voltage s tested (-90 to +50 mV), showed outward rectification and showed no o bvious time or voltage dependence. Its magnitude was 3.5-fold that of the total resting membrane current measured before LH treatment. LH is known to elevate cyclic AMP in these cells. We found that addition of the cAMP analog Sp-cAMPS mimicked LH in inducing chloride currents in these cells. We conclude that LH can activate a chloride conductance in granulosa cells, and that this action may be mediated by cAMP. Copy right (C) 1997 Elsevier Science Inc.