Angiotensin and angiotensin receptors in cartilaginous fishes

In mammals, a principal bioactive component of the renin-angiotensin system (RAS), angiotensin II (ANG II), is known to be vasopressor, dipsogenic, a stimulant of adrenocortical secretion and to control glomerular and renal t ubular function. Historically, a RAS analogous to that found in mammals was thought to have first evolved in the bony fishes. Recent research has iden tified the unusually structured elasmobranch [Asp(1)-Pro(3)-Ile(5)] ANG II. Physiological studies have demonstrated that ANG II in elasmobranchs is va sopressor, and stimulates interrenal gland production of the elasmobranch c orticosteroid 1 alpha -hydroxycorticosterone. The specific binding of ANG I I in elasmobranchs has been reported in gills, heart, interrenal gland, gut and rectal gland. The precise osmoregulatory role ANG II plays in cartilag inous fishes is not yet known; however, putative evidence is emerging for a role in the control of drinking rate, rectal gland secretion, and kidney f unction. (C) 2001 Elsevier Science Inc. All rights reserved.