Effects of arginine vasopressin (AVP) deficiency on basal mean arterial blood pressure in the rat

Abstract

The role of AVP controlling the mean arterial blood pressure (MBP) in basal conditions remains unclear. We described that neurointermediate pituitary lobectomy (NIL) in rats, induced an early but transient diabetes insipidus and low MBP (8 weeks after lobectomy). To elucidate the chronological effects of NIL, we evaluated the AVP serum levels, water intake and urine output (diabetes insipidus, DI), and MBP immediately (0 to 6 hours post NIL) and 3, 15, 45 and 90 days post NIL. The renin, angiotensin II and aldosterone system (RAAS) was assessed at 3 and 45 days post NIL. Values were compared with the respective SHAM operated groups. Results: NIL caused significant and permanent AVP serum level decrease (10.6 ± 0.8 vs 2.4 ± 0.16 pg/ml (SD), SHAM vs NIL), transient DI (15‐30 days of duration) and permanent decrease of the MBP in 70% of the NIL animals (106.8 ± 3.15 vs 73.8 ± 3.2 mmHg). Hypotension was apparent 20‐30 minutes after NIL. No significant differences in the RAAS were evident.ConclusionsWe propose that in non‐stressed animals, basal serum levels of AVP are required to maintain the hydro‐electrolytic balance and MBP. Further studies are needed to explain why some animals did not develop hypotension, and to determine how cardiovascular, renal and hormone adaptive mechanisms in the NIL group support their survival.Supported by UAA‐PIFF and CONACYT, México and the Jarislowsky and L. Carr‐Harris Foundations

Arginine vasopressin deficiency and conivaptan (a V1a–V2 receptor antagonist) treatment reverses liver damage and fibrosis in rats with chronic portocaval anastomosis

“…It is characterized by liver metabolic and haemodynamic alterations, 8,9 liver atrophy, 28 morphological and pathophysiological changes, decreased glycogen content, increases in ALT and AST serum levels, total and unconjugated hyperbilirubinaemia, low serum urea levels, hyperammonaemia and liver failure and fibrosis 8,9,23,29 . In rats, NIL induces prompt but transient diabetes insipidus (2–3 weeks duration post‐surgery) and permanent low circulating levels of AVP (80%) and oxytocin (90%) 30,31 . Almost all immune cells, as well as hepatic stellate cells and liver myofibroblasts, possess AVP receptors, 22,30 and AVP is an immunomodulatory hormone 11 .…”

“…8,9,23,29 In rats, NIL induces prompt but transient diabetes insipidus (2-3 weeks duration post-surgery) and permanent low circulating levels of AVP (80%) and oxytocin (90%). 30,31 Almost all immune cells, as well as hepatic stellate cells and liver myofibroblasts, possess AVP receptors, 22,30 and AVP is an immunomodulatory hormone. 11 Vaptans are synthetic drugs that interact with AVP receptors and block the effects of AVP on target cells.…”