Endothelin receptor subtypes and stimulation of aldosterone secretion.
Endothelins (ETs) are 21-amino acid peptides with two disulfide bonds that have powerful vasoactive properties. We have previously shown the presence of a specific, high-affinity, saturable receptor for porcine or human endothelin (ET-1) in cultured calf zona glomerulosa cells. ET-1 was a stimulator of aldosterone secretion although not as powerful as angiotensin II. Incubations of cultured calf zona glomerulosa cells with Sarafotoxin S6b (S6b), a snake venom that has a structure highly homologous to ET-1, stimulated aldosterone secretion with a potency similar to that of ET-1. Binding of [125I]ET-1 to the adrenal receptor gave a Kd of 0.17 +/- 0.05 nM and a Bmax of 36 +/- 8.5 fmol/well (n = 4). Displacement of [125I]ET-1 by unlabeled ETs and S6b showed that the concentrations needed to displace 50% of the tracer were 0.3 nM for ET-1, 0.3 nM for ET-2, 10 nM for S6b, and 100 nM for ET-3. Binding of [125I]S6b to cultured adrenal cells revealed a receptor with a Kd of 0.05 +/- 0.01 nM and a Bmax of 8 +/- 2 fmol/well (n = 4). Displacement of [125I]S6b by unlabeled ETs and S6b showed that the concentrations needed to displace 50% of the tracer were 0.03 nM for S6b, 0.06 nM for ET-1, 0.04 nM for ET-2, and 0.05 nM for ET-3. Unlabeled ET-1 and ET-2 preferentially down-regulated the binding of [125I]ET-1, and S6b preferentially down-regulated the binding of [125I]S6b.(ABSTRACT TRUNCATED AT 250 WORDS)
Gomez-Sanchez
C E
CE
Department of Internal Medicine, University of South Florida Health Sciences Center, Tampa.
Cozza
E N
EN
Foecking
M F
MF
Chiou
S
S
Ferris
M W
MW
D000450:Aldosterone / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D015536:Down-Regulation; D016232:Endothelins; D004730:Endothelium, Vascular; D010455:Peptides / Q000378:metabolism / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D017466:Receptors, Endothelin; D014662:Vasoconstrictor Agents; D014757:Viper Venoms / Q000378:metabolism / Q000494:pharmacology
D016232:Endothelins; D010455:Peptides; D011956:Receptors, Cell Surface; D017466:Receptors, Endothelin; D014662:Vasoconstrictor Agents; D014757:Viper Venoms; C057354:sarafotoxins s6; D000450:Aldosterone