Effect of plasma from essential hypertensives on tension of aortic strips.
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.
Zidek
W
W
Med. Poliklinik, Univ. Münster, W. Germany.
Bachmann
J
J
Schlüter
H
H
Witzel
H
H
Storkebaum
W
W
Sachinidis
A
A
D000328:Adult; D000818:Animals; D001011:Aorta / Q000502:physiology*; D001794:Blood Pressure; D002118:Calcium / Q000494:pharmacology; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood* / Q000503:physiopathology; D066298:In Vitro Techniques; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D009543:Nifedipine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D051381:Rats; D011921:Rats, Inbred WKY; D012016:Reference Values; D014661:Vasoconstriction
D009543:Nifedipine; D002118:Calcium; D010646:Phentolamine