Capillary recruitment is impaired in essential hypertension and relates to insulin's metabolic and vascular actions.
OBJECTIVE
In patients with essential hypertension, defects in both the metabolic and vascular actions of insulin have been described. Impaired microvascular function, a well-established abnormality in essential hypertension, may explain part of these defects. In the present study we investigated whether microvascular function is impaired in essential hypertension and relates to insulin's metabolic and vasodilatatory actions.


METHODS
We measured 24-h ambulatory blood pressure, capillary recruitment after arterial occlusion, and skin blood flow responses to iontophoresis of acetylcholine and sodium nitroprusside in 18 subjects with untreated essential hypertension and in 18 control subjects. Whole body insulin sensitivity and leg insulin-mediated vasodilatation were assessed with the hyperinsulinaemic clamp technique and plethysmography.


RESULTS
Hypertensive, as compared to normotensive, subjects had a decreased insulin sensitivity (0.8+/-0.3 vs. 1.7+/-0. 6 mgkg(-1)min(-1) per pmoll(-1); P<0.001), capillary recruitment after arterial occlusion (21.5+/-5.8 vs. 45.9+/-10.4%; P<0.001), acetylcholine-mediated vasodilatation (331+/-84 vs. 688+/-192%; P<0. 001), and insulin-mediated vasodilatation (median 29.3 vs. 47.2%; P<0.05). Correlation analyses with adjustment for sex, age, body mass index and waist-to-hip ratio showed significant relationships of capillary recruitment after arterial occlusion with blood pressure (r=-0.68; P<0.01), insulin sensitivity (r=+0.55; P<0.01) and insulin-mediated vasodilatation (r=+0.51; P<0.05), which extended from the normotensive to the hypertensive range.


CONCLUSIONS
Skin microvascular function is associated with blood pressure and insulin's metabolic and vasodilatatory actions, both in normotensive and hypertensive subjects. These findings offer a potential mechanistic explanation of the links among insulin resistance, impaired insulin-mediated vasodilatation and hypertension.
Serné
E H
EH
Department of Medicine, Academic Hospital Vrije Universiteit, De Boelelaan 1117, 1007 MB, Amsterdam, The Netherlands.
Gans
R O
RO
ter Maaten
J C
JC
ter Wee
P M
PM
Donker
A J
AJ
Stehouwer
C D
CD
D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000502:physiology; D002196:Capillaries / Q000473:pathology / Q000503:physiopathology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006973:Hypertension / Q000473:pathology / Q000503:physiopathology*; D007328:Insulin / Q000502:physiology*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012867:Skin / Q000098:blood supply*; D014664:Vasodilation / Q000502:physiology*
D007328:Insulin