Endothelin-1 receptors in rat renal glomeruli.

Renal glomeruli form a dynamic structure capable of regulating the glomerular filtration rate (GFR). To explore possible regulating effects of endothelin-1 (ET-1) upon glomerular functions, the presence of specific ET-1 receptors and the biological actions of ET-1 were studied in isolated rat renal glomeruli. The specific binding of [125I]ET-1 to glomeruli was time and temperature dependent. Scatchard analysis of the binding data indicated the presence of a single class of high-affinity binding sites with the apparent dissociation constant of 8.3 nM and the maximal binding capacity of 1.5 pmol/mg protein. ET-1 stimulated prostaglandin (PG) E2 production in glomeruli with the time course and the concentration dependency similar to those found in [125I]ET-1 binding to glomeruli. These results indicate the presence of high-affinity binding sites for ET-1 linked to PGE2 production in glomeruli, suggesting a possible role of ET-1 in the regulation of glomerular function.