Plasma from essential hypertensive patients contains a vasopressor agent (1000-1500 Da) that directly induces contraction in arterial smooth muscle, likely by increasing calcium influx.
Should not yet change hypertension management; hypothesis-generating for a circulating vasoconstrictor factor in essential hypertension.
The effect of fractions of plasma from essential hypertensive (n = 27) and normotensive subjects (n = 26) on the tension of aortic strips (n = 27) from normotensive rats was examined. The fractions obtained from hypertensive patients had been shown to increase blood pressure, when injected intravenously in a normotensive rat. In aortic strips the hypertensive fractions elicited a transient relaxation of variable amplitude and subsequently a sustained contraction. The normotensive fractions did not alter tension of the strips significantly. In Ca2+ free medium and after addition of nifedipine hypertensive plasma fractions did not induce a contraction, whereas in Na+ free medium the contraction was not abolished. It is concluded that in the fraction of hypertensive plasma containing substances with a molecular weight in the range of 1000-1500 Da a vasopressor agent with direct actions on arterial smooth muscle is present. The substance probably acts by increasing Ca2+ influx in vascular smooth muscle.
No takes yet. Share an insight, caveat, or question.
Zidek et al. (1990) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: