Effect of exogenous urotensin-II on vascular tone in skin microcirculation of patients with essential hypertension.
BACKGROUND
Plasma levels of urotensin-II (U-II) have been found to be elevated in patients with essential hypertension. However, the consequence of activation of the U-II system have not been previously determined in these patients. We therefore compared the effect of exogenous U-II administration on vascular tone in hypertensive patients (n = 13) and normotensive subjects (n = 14).


METHODS
The effect of U-II on vascular tone was determined in the forearm skin microcirculation using iontophoresis to administer the drug and laser Doppler velocimetry to measure microvascular response.


RESULTS
The U-II administration was associated with a dose-dependent vasodilator response from baseline in normotensive subjects (U-II 1 x 10(-12) mol/L, 609 +/- 164; U-II 1 x 10(-9) mol/L, 839 +/- 216; U-II, 1 x 10(-7) mol/L, 1249 +/- 228 arbitrary flux units; P < .0005). A dose-dependent vasoconstrictor response was observed in hypertensive patients compared to baseline (U-II 1 x 10(-12) mol/L, 60 +/- 212; U-II 1 x 10(-9) mol/L, -288 +/- 172; U-II, 1 x 10(-7) mol/L, -607 +/- 165 arbitrary flux units; P < .005). Differences in flow between the two groups were significant at the 1 x 10(-9) mol/L and 1 x 10(-7) mol/L dose levels (P < .001). In contrast, there was no significant difference in flux between baseline and U-II in either group (or between groups) when the opposite polarity was applied.


CONCLUSIONS
The demonstration of opposing effects of exogenous U-II in patients with hypertension and normal subjects suggests that U-II may be contributory to the increased vascular tone of these patients.
Sondermeijer
Brigitte
B
Department of Medicine, Monash University, The Alfred Hospital, Commercial Road, Melbourne, Victoria 3004, Australia.
Kompa
Andrew
A
Komesaroff
Paul
P
Krum
Henry
H
D000109:Acetylcholine / Q000008:administration & dosage / Q000494:pharmacology; D000279:Administration, Cutaneous; D001783:Blood Flow Velocity / Q000187:drug effects; D005260:Female; D005542:Forearm / Q000098:blood supply; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D007478:Iontophoresis / Q000379:methods; D008297:Male; D008833:Microcirculation / Q000187:drug effects; D008875:Middle Aged; D009599:Nitroprusside / Q000008:administration & dosage / Q000494:pharmacology; D012867:Skin / Q000098:blood supply*; D014579:Urotensins / Q000008:administration & dosage / Q000494:pharmacology*; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000494:pharmacology
D014579:Urotensins; D014665:Vasodilator Agents; D009599:Nitroprusside; C029677:urotensin II; D000109:Acetylcholine