Muscular ETBReceptors Develop Postnatally and Are Differentially Distributed in Specific Segments of the Rat Vasculature

Abstract

The endothelin/endothelin-receptor system is a key player in the regulation of vascular tone in mammals. We raised and characterized an antiserum against rat ETBreceptor and investigated the distribution of ETBreceptors in different vascular beds during postnatal development (day 0 through day 28) and in the adult rat. We report the tissue-specific and age-dependent presence of vasoconstrictor ETBreceptors. At the time of birth, vascular smooth muscle cells from all tissues examined did not exhibit ETBreceptor immunoreactivity. The occurrence of ETBreceptor immunoreactivity in the postnatal development was time dependent and started in small coronary and meningeal arteries at day 5, followed by small mesenteric arteries as well as brachial artery and vein at day 14. At day 21, ETBreceptors were present in the media of muscular segments of pulmonary artery, large coronary arteries, and intracerebral arterioles. At day 28, ETBreceptor immunoreactivity was evident in interlobular renal arteries, vas afferens, and efferens. Large renal arteries, mesenteric artery, and elastic segments of pulmonary arteries, as well as coronary and mesenteric veins, did not exhibit ETBreceptor immunoreactivity. These data demonstrate the age-dependent and tissue-specific presence of ETBreceptors, mainly on arterial smooth muscle cells in the vascular system of the rat.