Prolonged rat heart allograft survival after treatment with angiotensin converting enzyme inhibitor or a calcium antagonist.

The effect in vivo of the angiotensin converting enzyme (ACE) inhibitors captopril and enalapril and the calcium antagonist verapamil was studied in an experimental model using rat heart allografts. Daily post-transplant treatment of recipient rats (DA strain) with verapamil (75 mg kg-1 day-1) or captopril (40 mg kg-1 day-1) significantly prolonged survival of allografts from donors (PVG/c strain) when compared with an untreated control group (p < 0.05). No synergistic effect was observed when the two drugs were used for combined treatment. An equipotent does of enalapril (12.5 mg kg-1 day-1) caused no change in allograft survival of statistical significance. The results support the hypothesis that verapamil and captopril have effects on the immune reactivity in vivo, and that this is not a characteristic shared by all ACE inhibitors.