Cold-induced vasodilatation and peripheral blood flow under local cold stress in man at altitude.
ABSTRACT The cold-induced vasodilatation (CIVD) response was studied on 17 lowlanders (20-30 years) at Delhi, using a water bath maintained at 4 degrees+/-0.2 degreesC. The temperatures were measured at the tip of the index finger, centre of the palm, over a prominent wrist vein, and orally. Then the subjects were air-lifted to an altitude of 3500 m, where the measurements were repeated at weekly intervals for a period of 3 weeks. After this, they were flown back and retested. For comparison, the study at altitude was done on 10 acclimatised lowlanders and on 10 high-altitude natives. The peripheral blood flow under a local cold stress was calculated. Three types of CIVD responses--viz. typical hunting, proportional control, and continuous rewarmin--were observed. At altitude, the pattern was more or less the same but there was a significant reduction in the response. The responses of the natives were more or less identical to those of the lowlanders at sea level, and responses of the acclimatized lowlanders were better than the fresh inductees, but much less than the natives. The changes in peripheral blood flow was in accordance with the CIVD response.
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ABSTRACT: The study examined the effects of a 10-day normobaric hypoxic confinement (FiO2: 0.14), with (HT; n = 8) or without (HA; n = 6) exercise, on the hand-temperature responses during and after local cold stress. Before and after the confinement, subjects immersed their right hand for 30 min in 8°C water (CWI), followed by a 15-min spontaneous rewarming (RW), while breathing either room air (AIR), or a hypoxic gas mixture (HYPO). The hand-temperature responses were monitored with thermocouples and infrared-thermography. The confinement did not influence the hand-temperature responses of the HA group during the AIR and HYPO CWI and the HYPO RW phases; but it impaired the AIR RW response (-1.3°C; P = 0.05). After the confinement, the hand-temperature responses were unaltered in the HT group throughout the AIR trial. However, the average hand-temperature was increased during the HYPO CWI (+0.5°C; P ≤ 0.05) and RW (+2.4°C; P ≤ 0.001) phases. Accordingly, present findings suggest that prolonged exposure to normobaric hypoxia per se does not alter the hand-temperature responses to local cooling; yet, it impairs the normoxic rewarming response. Conversely, the combined stimuli of continuous hypoxia and exercise enhance the finger cold-induced vasodilatation and hand-rewarming responses, specifically, under hypoxic conditions.Scandinavian Journal of Medicine and Science in Sports 06/2014; DOI:10.1111/sms.12291 · 3.17 Impact Factor
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ABSTRACT: Abstract Keramidas, Michail E, Roger Kölegård, Igor B. Mekjavic, and Ola Eiken. Acute effects of normobaric hypoxia on hand-temperature responses during and after local cold stress. High Alt Med Biol 15:000-000, 2014.-The purpose was to investigate acute effects of normobaric hypoxia on hand-temperature responses during and after a cold-water hand immersion test. Fifteen males performed two right-hand immersion tests in 8°C water, during which they were inspiring either room air (Fio2: 0.21; AIR), or a hypoxic gas mixture (Fio2: 0.14; HYPO). The tests were conducted in a counterbalanced order and separated by a 1-hour interval. Throughout the 30-min cold-water immersion (CWI) and the 15-min spontaneous rewarming (RW) phases, finger-skin temperatures were measured continuously with thermocouple probes; infrared thermography was also employed during the RW phase to map all segments of the hand. During the CWI phase, the average skin temperature (Tavg) of the fingers did not differ between the conditions (AIR: 10.2±0.5°C, HYPO: 10.0±0.5°C; p=0.67). However, Tavg was lower in the HYPO than the AIR RW phase (AIR: 24.5±3.4°C; HYPO: 22.0±3.8°C; p=0.002); a response that was alike in all regions of the immersed hand. Accordingly, present findings suggest that acute exposure to normobaric hypoxia does not aggravate the cold-induced drop in hand temperature of normothermic males. Still, hypoxia markedly impairs the rewarming responses of the hand.High altitude medicine & biology 03/2014; 15(2). DOI:10.1089/ham.2013.1131 · 1.82 Impact Factor