Effect of Enalapril in Subjects With Hypertension Associated With Moderate to Severe Renal Dysfunction

The purpose of this study was to define the effect of the angiotensin-converting enzyme inhibitor, enalapril maleate, on blood pressure, renal function, protein excretion, and potassium homeostasis in patients with hypertension associated with moderate to severe renal dysfunction. Nine patients, having an initial inulin clearance between 9 and 48 mL/min/1.73 m2, were treated with enalapril monotherapy (n = 6) or enalapril/furosemide (n = 3) combination therapy. Systolic and diastolic blood pressures were well controlled. Supine plasma renin activity was stimulated; the supine plasma aldosterone level was suppressed, with a resultant increase in the serum potassium level. Clinical hyperkalemia was not observed. Glomerular filtration rate, assessed by inulin and creatinine clearances, was not significantly changed. Effective renal plasma flow, assessed by paraaminohippurate clearance was significantly increased, with a resultant decrease in filtration fraction. Importantly, urinary protein excretion was markedly reduced. These results suggest that enalapril therapy produces efferent arteriolar dilitation with preservation of the glomerular filtration rate. Enalapril therapy may also blunt the effects of angiotensin II on transglomerular passage of protein, as demonstrated by reduced proteinuria. These findings suggest that interruption of the renin-angiotensin system in patients with preexisting renal disease may have renal protective effects.