Role of arginine vasopressin in blood pressure control in young rats.
We investigated the importance of arginine-vasopressin (AVP) for blood pressure control in young and adult rats. Most of the studies were performed on Brattleboro rats with complete diabetes insipidus (DI). In some protocols, Sprague-Dawley rats (SD) were also used. The rats were age 20-24 days (young) or 50-80 days (adult). Adult DI rats have a significantly higher mean arterial pressure (MAP) than adult SD rats. The studies were performed during normovolemia and hypovolemia. Hypovolemia was created by the rapid withdrawal of blood, 0.5-1.5% of body weight. Following bleeding 0.5% of the body weight, young DI rats had a significantly larger decrease in MAP than adult DI and young and adult SD rats. Continuous infusion of AVP (2000 pg X 100 g-1 min-1) blunted the hemorrhagic hypotension in the DI rats. In all groups of rats studied, AVP had little effect on the MAP during normovolemia. The effect of AVP (given in a bolus dose of 20 or 2000 pg X 100 g-1) on the MAP was in DI rats significantly related to the MAP immediately prior to the AVP administration. No effect on MAP was observed when the initial MAP was 105-112 mm in the young DI rats and 148-157 mm in the adult DI rats. The effect of AVP (20 pg X 100 g-1) appeared to be submaximal to maximal. In anaesthetized SD rats, the basal AVP production was higher in the young than in the adult animals. Following bleeding, serum AVP increased in both young and adult rats but the increase was significant only in the adult rats.
D000375:Aging; D000818:Animals; D001127:Arginine Vasopressin / Q000502:physiology*; D001794:Blood Pressure; D001810:Blood Volume; D003919:Diabetes Insipidus / Q000503:physiopathology; D006439:Hemodynamics; D051381:Rats; D011910:Rats, Brattleboro; D011919:Rats, Inbred Strains
D001127:Arginine Vasopressin