EFFECT OF CAPTOPRIL ON INTRACELLULAR PH IN VASCULAR SMOOTH-MUSCLE CELLS

AIM: To observe the effect of captopril (Cap) on intracellular pH (pH( i)) in aortic smooth muscle cells (ASMC). METHODS: Cultured ASMC deriv ed from rat and rabbit aortae were loaded with the fluorescent dye BCE CF and pH(i) was determined using digital image processing method. RES ULTS: The pH(i) of untreated SHR and WKY rats were 7.37 +/- 0.29 and 7 .19 +/- 0.31, respectively. Oral Cap decreased pH(i) (7.11 +/- 0.26, P < 0.05) and exaggerated pH(i) response to angiotensin II (Ang-II, 0.1 mu mol . L(-1)) in ASMC of SHR rats vs WKY rats (0.14 +/- 0.05 vs 0.2 1 +/- 0.05 pH units, P < 0.01). Cap in vitro had no effect on Ang-II i nduced intracellular alkalinization in ASMC of rabbits. CONCLUSION: Or al Cap inhibits Na+ - H+ exchange activity in ASMC of SHR rats.