Endocrine and hemodynamic responses to dopamine infusion in the guinea-pig: effects of ACE inhibition with perindopril.

The effects of dopamine on plasma renin-angiotensin-aldosterone system vasopressin levels and blood pressure were studied in anesthetized guinea-pig. The inhibition of the angiotensin converting enzyme with perindopril permitted assessment of the role of the renin-angiotensin system. In perindopril-treated guinea-pigs, the activity of angiotensin-converting enzyme was decreased by 90% with simultaneous increases in plasma renin activity and angiotensin I concentration; aldosterone and vasopressin levels, blood pressure and heart rate were not modified. Dopamine depressed mean arterial pressure by 30% and increased heart rate (8%) in controls. Dopamine infusion did not affect either plasma renin activity or angiotensin I concentration or angiotensin-converting enzyme activity in control animals. But in perindopril pretreated animals it further increased plasma renin activity (88%) and angiotensin I concentration (35%). Finally, in controls, dopamine infusion increased plasma vasopressin concentrations (91%) whereas this increase did not occur in perindopril treated animals.