Different vascular responses in glabrous and nonglabrous skin with increasing core temperature during exercise

Abstract

To elucidate the characteristics of vasomotor control in glabrous and nonglabrous skin during dynamic exercise, we compared the vascular responses in both areas to increasing core temperature during the cycle exercise for 30 min at different intensities in the range 20-60% of peak oxygen consumption (VO(2peak)) in a total of 13 male and four female subjects in two experimental protocols. Skin blood flow was monitored using laser Doppler flowmetry. In protocol 1, the slope of the relationship between esophageal temperature (T (es)) and cutaneous vascular conductance (CVC) in the early phase of the exercise decreased (P < 0.05) with increasing exercise intensity at glabrous sites (palm) but not nonglabrous sites (dorsal hand). In protocol 2, to examine whether a difference in vascular responses in the two areas is due to the adrenergic vasoconstrictor system, the release of norepinephrine from adrenergic nerves in forearm and palmar skin was blocked locally by iontophoresis of bretylium tosylate (BT). The administration of BT diminished completely the change of CVC in the palm during the exercise but did not alter the response in the forearm compared with the untreated site. In the two areas, neither the T (es) threshold for vasodilation nor the change in CVC above the threshold in the middle and late phase of the exercise was influenced by the intensity of the exercise. These results suggest that, in the early phase of the exercise, light-to-moderate exercise reduces in an intensity-dependent manner the thermal sensitivity for vasodilation in glabrous skin but not nonglabrous skin via an adrenergic vasoconstrictor pathway.

Palm cooling to reduce heat strain in subjects during simulated armoured vehicle transport

“…NBF was used to represent blood flow to the palm because both sites contain glabrous skin, which lacks active vasodilator capacity (Yamazaki and Sone 2006). Palm blood flow was not measured directly because this would have impeded palm contact with the cooling plate.…”

Assessment of Human Skin Microcirculation and Its Endothelial Function Using Laser Doppler Flowmetry

“…Vascular reactivity was assessed at two representative sites with different control mechanisms: glabrous and nonglabrous area, respectively. Namely, it has been shown that the hemodynamic changes associated with acute exercise differ between these two sites (Yamazaki & Sone, 2006). The amplitude of changes, expressed as CVC as well as the time in which the changes occur during exercise differ between these two sites which might point to different control mechanisms.…”

Non-thermal modification of heat-loss responses during exercise in humans

“…In contrast, other studies have shown that exercise intensity does not affect the threshold (Johnson 1979;Wenger et al 1975;Yamazaki and Sone 2006, Table 2). Although the results of these studies are not consistent, it is possible that the threshold may be influenced by exercise intensity, if the intensity is higher (Table 2).…”