Long-term haemodynamic effects of enalapril at rest and during exercise in essential hypertension

Twelve males with moderately severe essential hypertension (mean arterial pressure [MAP] ranging 113-162 mmHg) were studied at rest supine and sitting and during bicycle exercise (50, 100 and 150 W). Intraarterial blood pressure (BP), and heart rate (HR) were recorded continuously. Cardiac output (CO) was measured by dye dilution (Cardiogreen). After 6-8 months (enalapril dose 10-40 mg daily) patients were restudied. BP fell in all patients, at rest sitting from 184/107 mmHg to 150/87 (-19%) and during 100 W from 223/117 to 194/98 mmHg (p less than 0.001). Pretreatment total peripheral resistance index (TPRI) was greatly increased in all patients and fell from 4137 to 3651 dyn s cm-5 m2 (-16%) (p less than 0.05). No significant changes were seen in CO, HR or stroke volume. No side effects were seen. It is concluded that enalapril reduces BP in patients with moderately severe hypertension at rest and during exercise due to reduction in TPRI without significant changes in CO or HR.