Autoradiographic distribution in rat tissues ding sites for endothelin : a neuropeptide ?

KWEK~, CHIZUKO, MASASHI IMAI, YUKIO HIRATA, MASASHI YANAGISAWA, AND TOMOH MASAKI. Autoradiographic distribuemn in rat tissues of binding sites for endothelin: a neuropeptide? Am, J. Physiol. 256 (Regulatory Integrative Comp. Physiol 25): R858 “*R866, 1989.--Endothelin (ET) is a potent and long-acting vasoconstrictor peptide consisting of 21 amino acids arid recently isolated from a medium of cultured porcine endothelial cells. To determine the possible sites of ET action, we hate L.onducted autoradiography and receptor binding assays A kh “‘1 labeled ET in rat tissues. The displaceable binding sites of the ligand were widely distributed, not only in the arteries and heart but also in various other organs, e.g., brain, kidney, lung, adrenal gland, and intestine. The systemically injected ID did not cross the blood-brain barrier, whereas the lq+kd, applied in vitro, was mainly located in the hypothalamic arid t haldunk areas, lateral ventricular region, subfornical orGUI, globus pallidus, and caudate putamen. Both membrane preparations from the brain stem including diencephalon and from t,he heart ventricle had similar, specific, and high-affinity brrlding sites for 1251=ET~ We suggest that ET is involved in the regulaticin of a large variety of organ functions and may also act as a neuropeptide.