Abstract: AIM: To study the effects of the novel antihypertensive drug I_ptakalim hydrochloride (I_pt) on the secretion function of blood vessel endothelial cells. METHODS: Bovine aortic endothelial cells (BAEC) were obtained by using digestion technique.Effects of I_pt on the endothelin-1 (ET-1), prostacyclin (PGI₂) and nitric oxide (NO) secretion by BAEC were studied and effects of I_pt on the intracellular calcium concentration in BAEC were examined by miocrofluorometry of Fura-2/AM loaded cells.RESULTS: I_pt at 10^-6 mol·L^-1 or more could inhibit cultured bovine aortic endothelial cells from producing and releasing endothelin-1 in a concentrationdependent manner, together with an increase in NO production.Moreover, I_pt at 10^-4 mol·L^-1 or more induced a rapid elevation of intracellular calcium concentration in BAEC.CONCLUSION: I_pt can improve the balance between the release of relaxing and contracting factors from the endothelium by inhibiting ET-1 production and enhancing NO production in BAEC.The elevation effect of [ Ca²⁺] i by I_pt is essential for the cytoplasm synthesis of NO, and the effect may favorably enhance endotheliummediated dilation.

Key words: iptakalim hydrochloride, endothelial cells, endothelin-1, prostacyclin, nitric oxide