Reduced responsiveness of cutaneous microcirculation in essential hypertension--a pilot study.
OBJECTIVE
Our hypothesis states that the reactivity of the cutaneous microcirculation is reduced in patients with hypertension compared with healthy subjects. The objective was to verify the hypothesis by measuring microvascular function in hypertensive patients.


METHODS
The study was a controlled trial with two arms: 15 hypertensives and 15 normotensives were enrolled, aged 30-60 years, and in hypertensives, a diastolic blood pressure of > 90 mmHg. The hypertensive patients were compared with gender- and age-matched controls having a diastolic blood pressure < 90 mmHg. The patients were kept on their medication.


METHODS
The local cutaneous forearm blood flow was measured by Laser-Doppler flowmetry. The blood flow response to local warming (44 degrees C), to the endothelium-dependent vasodilator acetylcholine (ACh), or to the endothelium-independent dilators sodium nitroprusside (SNP) and calcitonin gene-related peptide (CGRP) administered by iontophoresis were determined. Inflammatory markers and NT-pro brain natriuretic peptide (NT-proBNP) levels in plasma was also measured. Electrocardiograms (ECG) were evaluated and the subjects answered a lifestyle questionnaire.


RESULTS
The percentage change in vasodilator response to CGRP was significantly lower in the hypertensives compared with normotensives, 285% (95% CI 86-484) vs 764% (95% CI 366-1162) of baseline, p < 0.05. The change to local warming was 2191% (95% CI 1574-2807) in normotensives vs 1384% (95% CI 852-1917) in the hypertensives, p < 0.05. The vasodilator response to ACh was 1249% (95% CI 895-1602) in the normotensives and 873% (95% CI 610-1136) in the hypertensives. The vasodilator response to SNP in the normotensives was 771% (95% CI 436-1107) and 682% (95% CI 416-948) in the hypertensive group. Plasma level of NT-proBNP was 90 ng/1 (95% CI 35-145) in normotensives vs 285 ng/l (95% CI 70-499) in hypertensives (p = 0.06). The ECGs showed a tendency towards left ventricular hypertrophy (LVH) in hypertensives.


CONCLUSIONS
Patients with essential hypertension had significantly reduced microvascular dilator responses to CGRP and to local warming. Also, there was a tendency towards reduced responses to ACh. This points towards a generally weaker responsiveness of the cutaneous microvessels in hypertensives and could be a contributing factor to the development of high blood pressure. Patients with essential hypertension also had a tendency of higher plasma levels of NT-proBNP, which could be seen as an early sign of organ damage.
Lindstedt
Isak H
IH
Department of Emergency Medicine, Clinical Sciences, University Hospital, Lund, Sweden. Isak.HarrysonLindstedt@skane.se
Edvinsson
Marie-Louise
ML
Edvinsson
Lars
L
D000109:Acetylcholine / Q000494:pharmacology; D000328:Adult; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology; D016022:Case-Control Studies; D005260:Female; D005542:Forearm / Q000098:blood supply; D006358:Hot Temperature; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000503:physiopathology*; D008297:Male; D008833:Microcirculation / Q000187:drug effects* / Q000503:physiopathology; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood; D010446:Peptide Fragments / Q000097:blood; D010865:Pilot Projects; D012867:Skin / Q000098:blood supply*; D014664:Vasodilation / Q000187:drug effects
D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain; D015740:Calcitonin Gene-Related Peptide; D000109:Acetylcholine