Endothelin (ET) has been suggested to be involved in acute graft rejection of kidney transplantation and cyclosporin A (CsA) nephrotoxicity. For clarification of the pathophysiological role of ET in the early post-transplantation period, plasma endothelin-1 (ET-1) was measured by specific radioimmunoassay in renal transplant recipients, patients on maintenance hemodialysis (HD) and healthy volunteers. Twelve transplant recipients were used in this study, 8 of whom were living related subjects and 4 cadaver. Plasma ET-1 and graft function were measured each day, from 1 day prior and 7 days following transplantation and every week up to 5 weeks postoperatively. Plasma ET was measured in 20 other transplant recipients with stable function (serum creatinine < or = 1.8 mg/dl), 20 maintenance HD patients with no residual renal function and 6 healthy volunteers. Mean plasma ET-1 was 13.0 +/- 4.5 pg/ml in 20 recipients with stable graft function, 21.7 +/- 6.5 in 20 HD patients and 1.5 +/- 0.4 in healthy volunteers. These differences are statistically significant (p < 0.02). Plasma ET-1 showed significant decrease from 21.8 +/- 7.2 pg/ml prior to transplantation to 12.8 +/- 4.0 when urinary output reached more than 1000 ml in living and cadaveric transplantation subjects. All three acute vascular rejections clearly indicated histologically increased plasma ET-1 accompanied by an increase in serum creatinine. A significant positive liner correlation was noted between plasma ET-1 and serum creatinine during the first week following living transplantation. Two patients with clinically and histologically suspected CsA nephrotoxicity showed transient increase in plasma ET-1.(ABSTRACT TRUNCATED AT 250 WORDS)