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.