[The cellular mechanism of angiotensin II inhibition on BKCa of ECV304 cell and the protective effect of gingko leaf extract].
OBJECTIVE: To observe the cellular mechanism of A II inhibition on Maxi-conductance calcium activated potassium channel (BKCa) in ECV304 cell membrane. METHOD: Using the cell-attached configuration of patch clamp technique. RESULTS: A II receptor antagonist saralasin (10(-7) mol/L) may block the inhibitory effect of A II (10(-7) mol/L). Phorbol ester (5 x 10(-8) mol/L) potentiated the effect of A II, while NO (10(-10) mol/L SNP) decreased the effect of A II and gingko leaf extract (800 micrograms/ml) activated BKCa and opposed the effects of A II. CONCLUSION: A II receptor mediates the inhibitory effect of A II on BKCa in ECV304, and PKC is involved in this inhibition. NO and ginkgo leaf extract protect BKCa from the inhibition of A II.