ET-1 EXCRETION IS URINE FLOW-DEPENDENT IN KIDNEY DONORS AND TRANSPLANT RECIPIENTS

Urinary endothelin-1 excretion (uET-1/min) has been reported to be ele vated under cyclosporin A (CsA) therapy in kidney transplant recipient s (KR). The possible flow-dependence of uET-1/min was not considered. Therefore, we studied the effect of water diuresis on uET-1/min in KR 1 year after transplantation and used kidney donors (KD) as controls. Urinary ET-1/min and urine flow (uFlow) were measured in 25 KR and in 21 KD before and 27 KD 1 year after surgery (KD-Nx) during water diure sis induced by oral hydration in a 12 h overnight collection. uET-1/mi n was correlated with uFlow. uET-1/min in 12-h overnight collection wa s similar in KD, KD-Nx, and KR (127 +/- 55, 110 +/- 42, and 122 +/- 53 pg/min respectively). Urine flow did not differ significantly among t he three groups (range 0.6-3.7 ml/min). uET-1/ min correlated signific antly with urine flow in KD, KD-Nx, and KR (r = 0.59, r = 0.42, and r = 0.53, p < 0.03, respectively). The slope of the three regression lin es was not different. There was no correlation of uET-1/min with CsA t rough level or dose. uET-1/min is urine flow-dependent during water di uresis. Because NaCl diuresis has been reported to have no influence o n uET-1/min, we hypothesize that uET-1/min is linked to the state of d iuresis or antidiuresis in the distal nephron. CsA therapy does not in fluence uET-1/min in a 12-h urine collection.