[Vasopressin, oxytocin and angiotensin receptors in mammals]

The synthesis of new radiolabelled compounds and the evolution of the techniques designed to study the hormonal receptors allow a better understanding of their properties. Three types of vasopressin receptors have been described: the V1a receptor of liver and blood vessels, the V1b receptor of hypophysis and the V2 receptor of kidney. Such a classification was based on two criteria: The structure of the binding site and the nature of the second messenger produced. The V2 receptor coupled positively to adenylate cyclase regulates the water reabsorption via the increase of intracellular cyclic AMP. The V1a and V1b receptors involved in glycogenolysis, contraction and probably neurotransmission mobilize intracellular calcium via a positive coupling to phospholipase C. These two receptors exhibit different recognition patterns for vasopressin analogues. In mammals, the oxytocin receptors are mainly involved in myometrial contraction and lactation. Their characterization are generally difficult since they also interact with vasopressin and are sometimes colocated with vasopressin receptors. As for V1 receptor, they are coupled to phospholipase C and mobilized intracellular calcium. The receptors of angiotensin II regulate the blood pressure by different mechanisms. They are coupled to at least two transduction mechanisms (positive coupling to phospholipase C and negative coupling to adenylate cyclase). Electrophysiological data seems to indicate that such receptor may also control a calcium channel. Yet different molecules (cAMP, calcium, inositol phosphates, diacyl-glycerol) trigger the hormonal effect of angiotensin II inside the cell.(ABSTRACT TRUNCATED AT 250 WORDS)