Heart failure, renal function, and angiotensin converting enzyme inhibitors.

In nonazotemic patients we suggest that ACE inhibitors initially depress GFR, perhaps due to a fall in renal blood flow in those patients in whom a substantial fall in blood pressure occurs with the first dose. Autoregulation of renal blood flow apparently remains intact, but autoregulation of the GFR is impaired during ACE inhibition. Our experience is that sodium and water retention usually ensue and plasma volume expands, leading to a temporary restoration of renal blood flow and GFR towards baseline. Serum sodium is usually reduced at this time, weight in increased, and blood pressure may be partly restored. After about 1-2 weeks, natriuresis begins, although sodium balance and weight probably are not restored to normal for 4-8 weeks. As the plasma volume contracts again, blood pressure falls further and the GFR declines. Renal blood flow, however, is maintained by preferential reduction in renovascular resistance.