Effect of captopril or verapamil on intracellular sodium in cultured vascular smooth muscle cells

摘要

The effects of captopril (Cap) and verapamil (Ver) alone and in combination on intracellular Na~+ concentration ([Na~+]_i) in cultured aortic smooth muscle cells (ASMC) of rabbits was evaluated by a direct measurement of [Na~+]_i with fluorescent dyesodium-binding benzofuran isophthalate (SBFI) combined with digital image. [Na~+]_i in resting cells was found to be 11.9 +- 0.7 mmol/L. Angiotensin II (Ang-II, 0.1-10 mu mol/L) induced an increase of [Na~+]_i in concentration-dependent manner. Ver (0.1-10 mu mol/L) inhibited Ang-II (1 mu mol/L)-induced increase in [Na~+]_i, while Cap enhanced Ang-II-induced increase in [Na~+]_i at 10 mu mol/L but not at 0.1-1 mu mol/L. Ver (0.1-1 mu mol/L)abolished enhancement of Ang-II-induced increase in [Na~+]_i byCap. Thus, the inhibition of Capenhanced [Na~+]_i by Ver may provide a new hypothesis for the underlying molecular mechanism of synergistic effect of the combination of Ca~(2+) antagonists and angiotensin-converting enzyme inhibitors in controlling bloodpressure.