Effects of plasma from hypertensive patients on the responses to angiotensin and norepinephrine in dogs and rats
Greenberg, S.; Boldstein, B.; Wilson, W.R.
Clinical Pharmacology and Therapeutics 15(4): 337-343
The effect of peripheral venous plasma (PVP) from normotensive sub;ects (Group A), and hypertensive patients who received placebo (Group B) or thiazide therapy (Group C) on vascular reactivity and resistance was evaluated in intact rats and dogs. Plasma electrolytes and serum levels of creatinine were normal in the three groups. Administration of 100 pl per kilogram of p Vp from Groups A, B, or C did not affect the systemic pressure or the pressor responses to norepinephrine (NE) and angiotensin (A) in the anesthetized rat. The canine paw was perfused with autologous blood at constant flow. Intra-arterial infusions of p Vp (0.5 ml per minute) from Groups A, B, and C transiently reduced vascular resistance by 23 ± 11 %,35 ± 8%, and 8 ± 6% respectively. However, paw perfusion pressure returned to control values within 30 minutes. Pressor responses to Ne were similar before and during infusion of p Vp from each group. The pressor responses to tyramine (T) were enhanced by 33% during infusion of p Vp from Group A and 67% (p < 0.05) and 62% (p < 0.05) during infusions of p Vp from Groups Band C, respectively. Since Pvp from Groups A, B, and C enhanced the pressor response to T but did not affect the response to NE, we conclude that a substance in human Pvp enhances T-induced catecholamine release. This substance probably does not play a role in essential hypertension.