Abstract
We examined the in vivo pressure-flow relationship in human cutaneous vessels during acute and repeated elevations of local transmural pressure. In 10 healthy men, red blood cell flux was monitored simultaneously on the nonglabrous skin of the forearm and the glabrous skin of a finger during a vascular pressure provocation, wherein the blood vessels of an arm were exposed to a wide range of stepwise increasing distending pressures. Forearm skin blood flux was relatively stable at slight and moderate elevations of distending pressure, whereas it increased approximately three- to fourfold at the highest levels (P = 0.004). Finger blood flux, on the contrary, dropped promptly and consistently throughout the provocation (P < 0.001). Eight of the subjects repeated the provocation trial after a 5-wk pressure-training regimen, during which the vasculature in one arm was exposed intermittently (40 min, 3 times/wk) to increased transmural pressure (from +65 mmHg week 1 to +105 mmHg week 5). The training regimen diminished the pressure-induced increase in forearm blood flux by ∼34% (P = 0.02), whereas it inhibited the reduction in finger blood flux (P < 0.001) in response to slight and moderate distending pressure elevations. The present findings demonstrate that during local pressure perturbations, the cutaneous autoregulatory function is accentuated in glabrous compared with in the nonglabrous skin regions. Prolonged intermittent regional exposures to augmented intravascular pressure blunt the responsiveness of the glabrous skin but enhance arteriolar pressure resistance in the nonglabrous skin.
Highlights
It is generally accepted that during pressure perturbations, the cutaneous vasculature exhibits some degree of autoregulatory capability
Anatomical and functional differences, exist between the glabrous and nonglabrous skin regions; namely, the former is heavily endowed with arteriovenous anastomoses (AVAs) and is innervated predominantly with adrenergic fibers, whereas the latter supposedly lacks AVAs and is regulated by both a sympathetic adrenergic vasoconstrictor system and a sympathetic cholinergic vasodilator system (11, 12)
The arterial and arteriolar stiffness increases after prolonged intravascular pressure loading evoked by 5 wk of intermittent local exposures to subatmospheric ambient pressure (15), whereas it decreases after sustained periods of pressure unloading ensued from 5 wk of horizontal bedrest (16, 17)
Summary
It is generally accepted that during pressure perturbations, the cutaneous vasculature exhibits some degree of autoregulatory capability. In this study, we initially tested the hypothesis that cutaneous autoregulatory function would be accentuated in the glabrous compared with in the nonglabrous skin regions during acute moderate-to-large elevations of local transmural pressure (series I). For this purpose, we monitored by means of laser-Doppler flowmetry, skin blood flux simultaneously on the dorsal side of the forearm and the ventral side of a finger during a vascular pressure provocation, during which the blood vessels of an arm were exposed to stepwise increasing distending pressures (24).
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