Responses of renal, coronary and vertebral vasculatures to MC-838 and captopril in anesthetized dogs.

The regional hemodynamic effects of MC-838, a new angiotensin-converting enzyme inhibitor, and captopril at equidepressor doses were examined in the anesthetized dog by simultaneously measuring renal (RBF), coronary (CBF), vertebral (VBF) arterial and aortic blood flow (AoF). Hemodynamic responses to angiotensin I (AI), AII and noradrenaline were compared before and after the administration of each inhibitor. MC-838 (3 mg/kg i.v.) lowered gradually aortic pressure (AoP) and increased moderately AoF and RBF up to 60 min after the administration. Captopril (0.1 mg/kg i.v.) lowered AoP immediately after the administration and increased AoF and RBF more shortly than MC-838. Neither inhibitor produced a marked change in VBF or CBF. The effects of the inhibitors in the renal vascular bed was much greater than that in vertebral and coronary vascular beds, although vascular resistance in all of them was significantly reduced. Each of the drugs inhibited the pressor and renal vasoconstrictor responses to AI. These results indicate that the renal vasculature is more sensitive to both MC-838 and captopril than vertebral and coronary vasculature, but MC-838 has a slower and longer-lasting action than does captopril.