The study aimed to assess whether a short-term, high-intensity cold acclimation protocol would modulate finger vasomotor [i.e., finger temperature (TF), cold induced vasodilation (CIVD)] responses and regional thermo-perception to localized cooling. Six men performed a hand cold provocation (consisting of a 30-min immersion in 8°C water), while being whole-body immersed, once, in 21°C water (i.e., cold trial; HYPO), and, the following day, in 35.5°C water (i.e., normothermic trial; NORM). The local cold provocations were repeated, in the same order, after 10 days. In the intervening period, the subjects undertook a whole-body cold acclimation pro-tocol, consisting of daily whole-body 14°C-water immersions for 5 consecutive days, for a maximum of 2 h, while the skin temperature of the right hand was maintained at 35.6 (0.1)°C. Thermal (rectal temperature, skin temperature, finger temperature) cardiorespiratory (mean arterial pressure (MAP), heart rate and oxygen uptake), and perceptual responses (thermal sensation and comfort, pain, affective valence) were monitored throughout the trials. The acclimation protocol resulted in hypothermic adaptation (i.e., habituation), which was characterized by a modest reduction in shivering and an attenuation of whole-body thermal discomfort. The main finding of the study was that, regardless of subjects’ thermal status, the 5-day whole-body cold acclimation protocol did not alter TF (P > 0.1) and CIVD responses (P > 0.2) during local cold stress. Yet, after the acclimation, the cold-induced increase in MAP was reduced and tended to be reduced during the HYPO (P = 0.05) and NORM (P = 0.14) local cold provocation trials, respectively. Furthermore, the perceived thermal discomfort and pain in the immersed hand appeared to be alleviated in all post-acclimation trials.

<p>In birds like the Zebra finch (Taeniopygia guttata) the female, but not the male develop a brood patch upon incubation of eggs. The brood patch functions to increase heat exchange between the bird and the eggs. Development of the brood patch includes de-feathering, increased vascularization and edema formation. The increased vascularization is due to the development of arteriovenous anastomoses, AVA. The AVA are thermoregulatory vessels involved in cold induced vasodilation, CIVD, demonstrated to occur in the brood patch. Nitric oxide, NO, which is a well known vasodilator is a candidate substance for involvement in CIVD. In this study a NO-generating gel was applied to the brood patch of male and female zebra finches. Vasodilation was found to be markedly larger in females than in males. The larger vasodilation in the female brood patch is probably because NO vasodilate AVA selectively more than any other vessels. The study also investigated whether vasodilation would cause an increase in brood patch temperature. No definite changes in brood patch temperature could be observed and no conclusions could be drawn in the matter.</p>

In birds like the Zebra finch (Taeniopygia guttata) the female, but not the male develop a brood patch upon incubation of eggs. The brood patch functions to increase heat exchange between the bird and the eggs. Development of the brood patch includes de-feathering, increased vascularization and edema formation. The increased vascularization is due to the development of arteriovenous anastomoses, AVA. The AVA are thermoregulatory vessels involved in cold induced vasodilation, CIVD, demonstrated to occur in the brood patch. Nitric oxide, NO, which is a well known vasodilator is a candidate substance for involvement in CIVD. In this study a NO-generating gel was applied to the brood patch of male and female zebra finches. Vasodilation was found to be markedly larger in females than in males. The larger vasodilation in the female brood patch is probably because NO vasodilate AVA selectively more than any other vessels. The study also investigated whether vasodilation would cause an increase in brood patch temperature. No definite changes in brood patch temperature could be observed and no conclusions could be drawn in the matter.