Abstract: AIM: To observe the effects of valsartan on the large-conductance calcium-activated potassium channel (BKCa)of smooth muscle cells isolated from hypoxia-pulmonary artery hypertension (PAH) rats. METHODS: Thirty second-grade healthy SD male rats aged 7 weeks were selected, and divided randomly into 3 groups: Group A was control group, Group B was PAH group and Group C was valsartan intervention group with 10 rats in each group. The mean pulmonary artery pressure(PAMP)was measured in 3 groups. The arteria mesenterica smooth muscle cell capacitance of membrane(Cm), potassium current, and the current after BKCa was blocked by tetraethylammonium(TEA)were recorded by whole cell patch clamp and the BKCa current and the BKCa current density were calculated. The BKCa protein expression was measured by immuno-histochemical stain. RESULTS: Compared with Group B, the PAMP was lower than that in Group A or Group C(P <0.01), the membrane capacitance, BKCa current, current density and iOD value in Group A were higher(P <0.05), the BKCa current, BKCa current density were increased at different degrees in Ggroup C (P <0.05), but there was no change in iOD value. CONCLUSION: Valsartan can effectively reduce pulmonary pressure in hypoxia- pulmonary artery hypertension rats. The mechanism was probably the BKCa was activiated by valsartan.

Key words: valsartan, large-conductance calciumactivated potassium channel, patch clamp technique, pulmonary artery hypertension