Effects of supervised exercise training on lower-limb cutaneous microvascular reactivity in adults with venous ulcers

Purpose: To investigate the effects of a 12-week supervised exercise programme on lower-limb cutaneous microvascular reactivity in adults with venous leg ulceration. Methods: Thirty-eight adults with unilateral venous ulceration who were being treated with lower-limb compression therapy (58% male; mean age 65 years; median ulcer size 5 cm2) were randomly allocated to exercise or control groups. Exercise participants (n=18) were invited to attend thrice weekly sessions of lower-limb aerobic and resistance exercise for 12 weeks. Cutaneous microvascular reactivity was assessed in the gaiter region of ulcerated and non-ulcerated legs at baseline and 3 months using laser Doppler fluxmetry coupled with iontophoresis of acetylcholine (ACh) and sodium nitroprusside (SNP). Cutaneous vascular conductance (CVC) was calculated as laser Doppler flux (AU)/mean arterial pressure (mmHg). Results: Thirty-seven participants completed follow-up assessments. Median class attendance was 36 (range 2 to 36). Analyses of covariance revealed greater peak CVC responses to ACh in the exercise group at 3 months in both the ulcerated (adjusted difference = 0.944 AU/mmHg; 95% CI 0.504 to 1.384) and non-ulcerated (adjusted difference = 0.596 AU/mmHg; 95% CI 0.028 to 1.164) legs. Peak CVC responses to SNP were also greater in the exercise group at 3 months in the ulcerated leg (adjusted difference = 0.882 AU/mmHg; 95% CI 0.274 to 1.491), but not the non-ulcerated leg (adjusted difference = 0.392 AU/mmHg; 95% CI -0.377 to 1.161). Conclusion: Supervised exercise training improves lower-limb cutaneous microvascular reactivity in adults with venous leg ulceration. Keywords Randomized controlled trial; Exercise; Ulceration; Vascular function; Laser Doppler fluxmetry; Iontophoresi

Calcium channel blockers blunt postural cutaneous vasoconstriction in hypertensive patients

The aim of this work was to test whether calcium channel blockers interfere with skin vasoconstrictor reflexes that minimize postural increases in capillary pressure and avoid fluid extravasation and eventually subcutaneous edema. Studies were conducted in 23 untreated mild to moderate essential hypertensives; drugs, either calcium channel blockers or not, were given for 2 weeks according to a crossover, sequence-randomized design. Skin blood flow was measured by laser Doppler flowmetry in two skin areas: (1) the dorsum of the foot, where arteriovenous anastomoses are poorly represented, and (2) the plantar surface of the great toe, where those anastomoses are predominant. Determinations were obtained both with the foot at heart level and with it placed passively 50 cm below the heart level; percent flow changes from the horizontal to the dependent position were the measure of postural vasoconstriction. Two dihydropyridine derivatives, amlodipine (10 mg UID) and nifedipine (60 mg UID), and verapamil (240 mg BID), a chemically unrelated compound, diminished to similar extents the postural fall in skin blood flow at the dorsum of the foot. Blockade of alpha1-adrenergic and AT-1 subtype angiotensin II receptors by doxazosin (4 mg UID) and losartan (50 mg UID), respectively, exerted no effect. Postural skin blood flow responses at the plantar surface of the great toe were unmodified during the pharmacological trials. Thus, calcium channel blockers of different chemical origins antagonized postural skin vasoconstriction at the dorsum of the foot. The data indicate altered postural capillary blood flow regulation, since arteriovenous anastomoses are anatomically absent at this site; the effect was independent of either alpha1-adrenoceptor or angiotensin II receptor antagonism. Interference with skin postural vasoconstrictor mechanisms may result in net filtration of fluid to the extravascular compartment. This mechanism might explain the as yet unknown pathogenesis of ankle edema during treatment with calcium antagonists