Pressor factors and cardiovascular pressor responsiveness in borderline hypertension.

Abstract

SUMMARYThe role of various pressor factors and cardiovascular responsiveness to norepinephrine or angiotensin II in the pathogenesis of borderline hypertension was evaluated. Exchangeable body sodium, blood volume, plasma renin activity, norepinephrine or dopamine levels, and norepinephrine or epinephrine excretion rates were similar between 24 patients with borderline hypertension (mean age 34 ± 4 (SEM) years and 22 normal subjects matched for age; the patients had a slight increase in supine plasma epinephrine. Pressor doses of norepinephrine or angiotensin II were significantly lower (p < 0.01 and 0.001, respectively) in the borderline hypertensive group. These findings suggest that borderline hypertension may be maintained by inappropriately increased cardiovascular response to norepinephrine and angiotensin II in the presence of normal sympathetic and renin activity and a normal body sodium-volume state.

Mechanism of increased alpha adrenergic vasoconstriction in human essential hypertension.

“…More specifically, investigations of regional vascular responses identified increased vasodilation to alpha-receptor antagonists (2) and greater vasoconstriction to alpha-agonists (3,4) in hypertensives compared to normotensives. Similarly, greater pressor responses to intravenous infusions of norepinephrine were observed in hypertensive subjects (5,6). In a subset of hyperten- 1. Abbreviations used in this paper: EHT, essential hypertension; FABF, forearm blood flow; iaAII, intraarterial angiotensin II; iaNE, intraarterial norepinephrine; mFAVR, minimum forearm vascular resistance; MAP, mean arterial pressure; PRA, plasma renin activity; TPR, total peripheral resistance.…”

Cardiovascular and plasma catecholamine responses to exercise in blacks and whites.

“…16 In a recent review Jette et al 17 concluded that there is a twofold to 10-fold increase in the risk of future hypertension for hyperresponders. Additionally, borderline hypertensive individuals 18 - 21 and normotensive offspring of hypertensive parents 22 -23 exhibit exaggerated blood pressure (BP) responses to exercise.…”

Exogenous insulin augments in healthy volunteers the cardiovascular reactivity to noradrenaline but not to angiotensin II.

“…On the other hand, converting enzyme inhibition has recently been shown to attenuate the increased cardiovascular reactivity in patients with essential hypertension, although not in patients with diabetes (41). If one assumes that also All levels were elevated by exogenous insulin, the absence of a change in All pressor dose may in fact signify an increase in cardiovascular reactivity to this hormone, as alterations in plasma levels of vasoactive substances clearly affect the pressor responsiveness to these substances and a negative correlation between the two has been reported (2,42).…”

“…Cardiovascular reactivity was assessed as previously reported in the literature (2)(3)(4)(5). After basal blood pressure (the mean of five measurements) was measured and baseline blood samples were drawn, an infusion with either NA (noradrenaline tartrate, Centrafarm, dissolved in 5% dextrose) or All (Hypertensin, Ciba Geigy, dissolved in 5% dextrose) was begun.…”