Why the study?
Does infused norepinephrine increase plasma renin activity compared to phenylephrine in normotensive men?
Does infused norepinephrine increase plasma renin activity compared to phenylephrine in normotensive men?
Norepinephrine increases plasma renin activity in normotensive men, unlike phenylephrine, suggesting a specific humoral effect of circulating norepinephrine.
No immediate clinical implications for hypertension; leaves open norepinephrine-specific renin effects for further study.
We compared the effects of infused norepinephrine (NE) to another alpha-adrenergic agonist, phenylephrine, in order to understand better the influence of circulating NE on plasma renin activity (PRA) in man. In matched groups of normotensive men, NE (80 ng/min/kg) or phenylephrine (800 ng/min/kg) raised blood pressure by 15 to 20 mm Hg and caused reflex decreases in heart rate of 8 to 10 beats per minute. Infused phenylephrine suppressed PRA by about 15%, whereas NE increased PRA by about 40% (P less than .02). This differential effect of alpha-agonists on PRA defines an important humoral effect of NE, which should be considered to be a "cardiovascular hormone."
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Licht et al. (1989) studied this question.
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