Effect of enalapril on blood pressure, renal function, and the renin-angiotensin-aldosterone system in cats with autosomal dominant polycystic kidney disease

Objective - To evaluate blood pressure, renal function, and the renin-angiotensin-aldosterone system (RAAS) in cats with autosomal dominant polycystic kidney disease (ADPKD) and to assess the effect of enalapril on these variables. Animals - 6 cats with ADPKD and 6 age-matched healthy cats. Procedure - To measure blood pressure and heart rate, a radiotelemetry catheter was placed in the left femoral artery of each cat. Baseline data collection included 24-hour blood pressure, heart rate, and motor activity. Blood was then collected for analysis of RAAS status and renal function. Enalapril (0.5 mg/kg of body weight, PO, q 24 h) was administered for 1 week, and data collection was repeated. Results - Differences in baseline blood pressure, heart rate, motor activity, RAAS status, and renal function were not detected between cats with ADPKD and control cats. Hypertension was not documented in cats with ADPKD. Blood pressure was significantly reduced for 15 to 17 hours after treatment with enalapril in both groups. Administration of enalapril also resulted in significant increases in plasma renin activity and significant decreases in angiotensin converting enzyme activity and atrial natriuretic peptide concentration but only minimal changes in glomerular filtration rate and effective renal plasma flow in both groups of cats. Conclusions and Clinical Relevance - Although hypertension is common in humans with ADPKD, cats with ADPKD were normotensive. Treatment with enalapril (0.5 mg/kg, PO, q 24 h) significantly reduced blood pressure in normotensive healthy cats and cats with ADPKD, and resulted in predictable changes in RAAS enzyme activities and hormone concentrations. Enalapril had minimal effects on renal function. (Am J Vet Res 1999;60:1516-1525).