RITMO CIRCADIANO DEL SISTEMA RENINA-ANGIOTENSINA-ALDOSTERONE IN SOGGETTI CON TRAPIANTO DI RENE E CUORE

The present investigation evaluates the circadian rhythm of renin-angiotensin-aldosterone system (RAAS) in subjects with kidney (KTS) or heart (HTS) transplantation undergoing conventional therapy with prednisone and cyclosporine. RAAS circadian rhythmicity has been compared with the circadian cycle of cortisol as a marker rhythm. The chronobiological exploration has been performed by measuring the circulating levels of plasma renin activity (PRA), plasma aldosterone (PA), and serum angiotensin-converting-enzyme (SACE) and plasma cortisol (PC) in serial samplings collected six times over a 24-h span. Time-qualified levels of plasma cyclosporine (CYCL) have been established. The control group consisted of 10 normal subjects matching in age and sex. Individual data series were analysed by the Cosinor method. The chronobiometric estimates demonstrate the lack of a circadian rhythmicity for PRA, PA and SACE in KTS and HTS. The PC circadian rhythm is demonstrable in KTS, but not in HTS. The abolition of the RAAS circadian rhythm in both KTS and HTS seems to be attributable to the effects exerted by CYCL. The disappearance of the PC circadian rhythm may be due to the prednisone therapy that is administered twice a day in HTS but not in KTS. The asynchronous effects of this drug lead us to suggest that antirejection therapy may be optimized by administering prednisone and cyclosporine according to a chronomodulated scheme.