SYSTOLIC MECHANICAL PERFORMANCE OF HETEROTOPICALLY TRANSPLANTED HEARTS IN RATS TREATED WITH CYCLOSPORINE

Objectives: The aim was to compare left ventricular mechanical perform ance of the heterotopic cardiac transplant undergoing atrophy and the in situ recipient hearts of immunosuppressed rats. Methods: The hearts of outbred male Wistar rats were transplanted, with a part of the lun gs, into the abdomen of recipients of the same strain by attaching the stump of the aorta end to side to the abdominal aorta of the recipien t. The animals were treated with cyclosporin A at a daily dose of 15 m g.kg-1 for seven consecutive days after the operation. Ventricular fun ction was assessed in the isolated perfused ''non-working'' heart unde r isovolumetric conditions. Results: Within three, 14, and 28 days aft er transplantation the mass of the left ventricle of the transplant de creased to 84, 54, and 43% compared with corresponding recipients. The developed pressure, maximum rate of pressure development, and the slo pe of the systolic stress-strain relation were unaffected in the atrop hic ventricles of the transplants; the rate of relaxation, however, si gnificantly decreased. Similar results were obtained with inbred Lewis rats receiving no immunosuppression. Conclusions: The data indicate t hat systolic mechanical performance of the heterotopically transplante d hearts was maintained during the development of atrophy; the cardiot oxic effect of cyclosporin did not manifest itself under these conditi ons.