Renal aspects of treatment by converting enzyme inhibitors in hypertension.

Converting enzyme inhibitors (CEI) are efficient antihypertensive medications. The acute and chronic effects of captopril (SQ) on renal function and electrolyte balance are analyzed in the present paper. Acute administration of SQ was associated with renal vasodilatation in the patients with essential hypertension (EH) but had no effect in normal subjects with similar renin levels thus suggesting an enhanced renal vascular response to CEI in EH. A variable effect of CEI on renal function was observed in renovascular hypertension; GFR fell when blood pressure decreased by more than 25 mmHg. Three cases of striking recovery of GFR during chronic SQ in young patients with malignant nephrosclerosis maintained on hemodialysis are reported. Such an improvement in GFR never occurred in patients with primary renal disease. When systemic and renal responses to acute isotonic saline loading were assessed, captopril blunted the exaggerated natriuretic response to saline loading observed in EH and unmasked the volume-dependence of arterial pressure. A case of hyperkalemia during treatment with SQ is reported in a patient with bilateral renal artery stenosis who developed moderate renal failure during treatment. This was associated with high plasma aldosterone whilst fractional excretion of K+ was inappropriately low for the level of serum creatinine thus suggesting that tubular unresponsiveness to aldosterone may have developed during SQ.