Cardiovascular effects of AVP and ANG in experimental pulmonic stenosis in rats
Riegger, G.A.; Albert, M.; Kochsiek, K.
American Journal of Physiology 254(3 Pt 2): H438-H442
1988
ISSN/ISBN: 0002-9513 PMID: 3348423 Document Number: 310502
Our objectives were to examine the role of vasopressin and renin in the regulation of peripheral vascular tone in an animal model of right ventricular failure due to chonic (10 wk) pulmonic stenosis. We tested in chronically instrumented conscious control rats and in rats with pulmonic stenosis on a normal and a high-sodium diet both vasoconstrictor systems by applying specific inhibitors. The rats with pulmonic stenosis showed significant hemodynamic changes, a hypertrophy of the right ventricle, increased levels of plasma renin concentration, and inappropriately elevated plasma levels of vasopressin in comparison to control animals. Plasma renin concentration was suppressed in the sodium-loaded controls. After the administration of a specific inhibitor of the vascular receptors of arginine vasopressin [30 .mu.g, d(CH2)5Tyr(Me)AVP], we found no hemodynamic changes in control rats on the normal diet, a reduction of mean arterial pressure in the sodium-loaded controls (4 .+-. 4 mmHg; P < 0.005), and in the animals with pulmonic stenosis and normal sodium intake (5 .+-. 5 mmHg; P < 0.001) and high-salt diet (6 .+-. 7 mmHg; P < 0.02). Intravenous bolus injection of teprotide (1 mg/kg) resulted in a decrease of mean arterial pressure in the control group (normal diet) of 9 .+-. 8 mmHg (P < 0.05). The fall of blood pressure (22 .+-. 10 mmHg; P < 0.001) in the rats with pulmonic stenosis was significantly greater (P < 0.01) and was strongly related to plasma renin concentration. Therefore, vasopressin and the renin-angiotensin system contribute to an increase of peripheral vascular tone in chronic pulmonic stenosis. The effect of vasopressin seems to be small in comparison to the renin system even though most animals had considerably elevated vasopressin levels. In sodium-loaded control rats it is suggested that vasopressin participates in the regulation of blood pressure.