The aim of the study was to evaluate the effects of verapamil sustained release (SR) 240 mg, enalapril and their combination on blood pressure (BP) and cardiac haemodynamics at rest and during exercise in 20 patients with moderate essential hypertension (seven men and 13 women, mean age +/- s.d. 53.7 +/- 15.8 years). After a 4 week placebo run-in period, patients were randomly allocated to received verapamil SR 240 mg once daily or enalapril 20 mg once daily for 4 weeks in a double-blind fashion. Patients whose diastolic blood pressure (DBP) was still > or = 95 mm Hg at the end of this period received verapamil SR plus enalapril for an additional 4 weeks. At the end of the placebo, single and combined treatment periods, resting and exercise (bicycle ergometry) haemodynamics were evaluated by radionuclide ventricular angiography (technetium-99m) and the following parameters were assessed: BP, heart rate, double product, systemic vascular resistances (SVR), cardiac output (CO), stroke volume (SV), ejection fraction (EF) mean ejection rate (mER) and peak filling rate (PFR). Both verapamil SR and enalapril monotherapies significantly reduced resting and exercise BP (P < 0.01), with a BP normalisation (DBP < or = 95 mm Hg) of five of 10 and 4 of 10 patients respectively. A greater BP fall and a normalisation of 11 of 11 patients was obtained in non-responders to monotherapy, when treated with verapamil SR and enalapril (P < 0.01). Verapamil SR also reduced heart rate at rest and during exercise (-11.8% and -18.4%, respectively, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)