THE EFFECT OF TACROLIMUS (FK506) AND CYCLOSPORINE-A (CYA) ON PERIPHERAL SEROTONERGIC MECHANISMS IN UREMIC RATS

The aim of this study was to investigate the mechanism of hypertension and thromboembolic events induced by cyclosporin (CyA) and tacrolimus (FK506) in respect to their action on the serotonergic blood system. The study was carried out on healthy rats and those with experimental chronic renal failure. CyA injected into healthy and uremic rats cause d an increase in serotonin (5-HT) concentration levels in whole blood and platelets. Concomitantly a rise in systolic blood pressure was obs erved. Platelet aggregation values were significantly higher in uremic rats given CyA. FK506 had no influence on 5-HT blood content, blood p ressure or platelet aggregation values. It is concluded that 5-HT may play a role in the development of hypertension and thrombotic events c aused by CyA. Furthermore, lower incidence of these complications duri ng FK506 treatment could be the result of this drug's limited effect o n the serotonergic blood system.