The peak effects of 10 mg nisoldipine p.o. with or without 80 mg propranolol p.o. on systemic and regional haemodynamics in conscious pigs were investigated. Nisoldipine increased heart rate (70%), cardiac output (67%) and maxLVdP/dt (75%), but decreased mean arterial pressure (21%) as systemic vascular conductance increased by 120%. Left ventricular systolic and end-diastolic pressures were not affected. Vasodilatation occurred in most organs. The increase in left ventricular blood flow (150%) favoured the epicardial (195%) over the endocardial (110%) layers. As a result the endo-epi blood flow ratio decreased by 30%. When nisoldipine was administered simultaneously with propranolol, heart rate (29%), cardiac output (35%) and systemic vascular conductance (65%) increased, but maxLVdP/dt did not change. Mean arterial (18%) and left ventricular systolic (10%) pressure decreased; left ventricular end-diastolic pressure was again unaffected. In most organs vasodilatation was attenuated, but still present, compared to the changes after nisoldipine alone. The increase in epicardial blood flow (70%) again exceeded that in endocardial blood flow (35%), however, the endo-epi ratio decreased by only 15%. In the presence of propranolol, nisoldipine did not exert a negative inotropic action while the reflex-tachycardia was attenuated. In addition, no detrimental effects on perfusion of regional vascular beds were observed.