INFLUENCE OF ANGIOTENSIN CONVERTING-ENZYME-INHIBITOR (CAPTOPRIL) ON KIDNEY EPITHELIAL-CELLS INVITRO - STUDIES ON POTASSIUM (RB-86) INFLUX AND CELLULAR PROLIFERATION

The effects of captopril on potassium influx and cellular proliferation in a dog kidney epithelial cell line (Madin-Darby canine kidney cells, MDCK) were studied. Na+K+-ATPase activity and the loop diuretic sensitive Na/K/2Cl- cotransport were measured using 86Rb as tracer substance. Cells were incubated with various concentrations of captopril (1-10 mmol/l). The furosemide sensitive Na/K/2Cl- cotransport was significantly decreased from 1 mmol/l onwards. Na+/K+-ATPase activity was lowered only when high amounts (10 mmol/l) of the drug were used. Cell proliferation was measured via [3H]thymidine incorporation. After incubation with 1 mmol/l captopril proliferation was strongly decreased (> 50%). Higher amounts (5-10 mmol/l) did not further suppress cell proliferation. The data suggest that natriuresis following ACE inhibition in vivo does not involve a direct effect of captopril on Na+K+-ATPase. However, the effect on cell proliferation may be of clinical relevance in respect to a possible mitogenic effect of angiotensin II. © 1990.