[125I]Endothelin-1 binding to renal brush border and basolateral membranes

[I-125]Endothelin-l bound with high affinity to a single site on both brush border membranes (K-d = 192 +/- 26 pM, B-max = 314 +/- 49 fmol/mg) and basolateral membranes (K-d = 94.7 +/- 3.4 pM, B-max = 612 +/- 107 fmol/mg) isolated from rat renal cortex. Competition binding experiments using subtype selective ligands revealed that the proportion of ETB to ETA receptors was 80:20 and 60:40 in the brush border membrane and the basolateral membrane, respectively. The results demonstrate that endothelin-1 binds to brush border membranes, and that endothelin ETB receptors may be involved in the previously described effects of endothelin-1 on brush border membrane Na+ transport. (C) 1998 Elsevier Science B.V.