title: Noninvasive estimation of increased structurally-based resistance to blood flow in the skin of subjects with essential hypertension.
abstract: A Laser-Doppler flowmeter was used to investigate the effect of essential hypertension on blood flow in maximally vasodilated skin, heated to 44 degrees C. Maximum Laser-Doppler flux (MLDF) was measured in 12 subjects with essential hypertension on no treatment and in 12 normotensive control subjects, and the resistance to flow was estimated by dividing pressure by flux. MLDF was not significantly different in the two groups: 3.69 +/- 0.87 V (arbitrary units, subjects with hypertension, mean +/- S.D.) vs 3.48 +/- 1.29 V (normotensive control subjects), despite the higher mean arterial pressure in the hypertensive group: 128.9 +/- 16.3 mmHg vs 91.8 +/- 9.1 mmHg (p less than 0.01). Resistance to flow was elevated in the subjects with hypertension: 37.2 +/- 12.8 mmHg/V vs. 29.6 +/- 10.4 (p = 0.05), and in the hypertensive group resistance was significantly correlated with mean arterial pressure (r = 0.69, n = 12, less than 0.025). Following two weeks vasodilator treatment in 6 of the hypertensive subjects, MLDF and mean arterial pressure fell, but the resistance remained elevated. These findings confirm the presence of a structurally-based increase in flow-resistance in the skin in subjects with hypertension, which prevents overperfusion of this tissue in the face of increased arterial pressure. The simple and noninvasive technique described herein could be used on a large scale to prospectively evaluate the reversibility (or otherwise) of structural resistance changes with pharmacological antihypertensive therapy.
authors.affiliation: Charing Cross and Westminster Medical School, London, England.
authors.forename: S A
authors.initials: SA
authors.lastname: Williams
authors.forename: J E
authors.initials: JE
authors.lastname: Tooke
mesh_terms: D006801:Humans; D006973:Hypertension / Q000188:drug therapy / Q000503:physiopathology*; D007834:Lasers; D012039:Regional Blood Flow; D012867:Skin / Q000098:blood supply*; D014655:Vascular Resistance / Q000502:physiology*; D014665:Vasodilator Agents / Q000627:therapeutic use
chemical_list: D014665:Vasodilator Agents