Effect of Vitamin C and E in Modulating Peripheral Vascular Response to Local Cold Stimulus in Man at High Altitude.

Abstract

At high altitude (HA), cold stress is aggravated by hypoxia, perhaps due to the increased formation of free radicals which trigger oxidative stress. This may be one of the contributing factors for adverse effects including disturbances in microcirculation and capillary permeability resulting in decreased peripheral blood flow. This leads to altered cold-induced-vasodilatation (CIVD) response on exposure to HA. The present study was conducted on 40 male volunteers (4 groups of 10 each) to evaluate the utility of supplementation of vitamin C (500 mg/d)and vitamin E (400 mg/d) singly, as well as in combination, in modulating peripheral vascular response by assessing CIVD response under local cold stimulus both at Delhi (200 m) and at HA (3,700 m). On exposure to 3,700 m, decreased CIVD response was observed in all the groups. The responses were better in vitamin supplemented groups, in general, as compared to the placebo group. The best CIVD response was seen in the vitamin C (singly)-treated group. Administration of vitamin C and E together did not result in any additional benefit. Facilitation of CIVD response due to supplementation of vitamin C may be attributed to its (a) antioxidant effect, and (b) major physiological functions of increased metabolism and thermogenic properties, facilitation of collagen synthesis, restoration of intercellular substances and better maintenance of the rheological status of the blood. Hence, vitamin C is effective for improving peripheral blood flow and thereby reduces the incidence of cold injuries during acclimatization or outdoor duties at HA.

Acute Effects of Normobaric Hypoxia on Hand-Temperature Responses During and After Local Cold Stress

“…It may appear that current results are in conflict with previous studies that have shown an enhanced cold-induced vasoconstriction during CWI of a hand at high-altitude (Daanen and van Ruiten, 2000;Mathew et al, 1977;1979;Purkayastha et al, 1999;Takeoka et al, 1993). However, in the aforementioned field studies, wherein the response to CWI was examined only in one finger, the preimmersion temperature of the digit was considerably lower in the tests performed at high-altitude than in those at sea-level.…”

“…However, in the above studies (Daanen and van Ruiten, 2000;Mathew et al, 1977;1979;Takeoka et al, 1993;Purkayastha et al, 1999), the temperature of the digits prior to the local cold provocation was significantly lower in the hypoxic than in the normoxic cold test, despite the similar general thermal status of the subjects; this effect appears not to have been taken into account when concluding that hypoxia potentiates the cold-induced vasoconstrictor response. In view of the fact that the cold tests were performed a few hours (Daanen and van Ruiten, 2000;Mathew et al, 1977) or days (Daanen and van Ruiten, 2000;Mathew et al, 1977;1979;Takeoka et al, 1993;Purkayastha et al, 1999) after the arrival of the subjects at high altitude, the enhanced peripheral vasoconstrictor tone was probably attributable either to the distinct effects of hypoxia (Heistad and Wheeler, 1970;Kollai, 1983), or to the synergistic actions of hypoxia and low ambient temperature (Cipriano and Goldman, 1975). Considering that the response magnitude of a physiological function may be significantly affected by its basal level of activity (cf.…”

“…In high altitude conditions, hypoxia coexists with a number of environmental (e.g., cold, wind) and behavioral (e.g., reduced physical activity and energy intake) components that, independently or synergistically, might constitute risk factors for local cold injury. To establish whether a causal relationship exists between hypoxia per se and cold injury, a number of studies (Daanen and van Ruiten, 2000;Mathew et al, 1977;1979;Purkayastha et al, 1999;Takeoka et al, 1993) examining the vasomotor responses of the extremities during local cold stress in controlled laboratory conditions at high altitude have suggested that systemic arterial hypoxia exaggerates the cold-induced cutaneous vasoconstriction and impairs any cold-induced vasodilatation (CIVD) response. However, in the above studies (Daanen and van Ruiten, 2000;Mathew et al, 1977;1979;Takeoka et al, 1993;Purkayastha et al, 1999), the temperature of the digits prior to the local cold provocation was significantly lower in the hypoxic than in the normoxic cold test, despite the similar general thermal status of the subjects; this effect appears not to have been taken into account when concluding that hypoxia potentiates the cold-induced vasoconstrictor response.…”

“…To establish whether a causal relationship exists between hypoxia per se and cold injury, a number of studies (Daanen and van Ruiten, 2000;Mathew et al, 1977;1979;Purkayastha et al, 1999;Takeoka et al, 1993) examining the vasomotor responses of the extremities during local cold stress in controlled laboratory conditions at high altitude have suggested that systemic arterial hypoxia exaggerates the cold-induced cutaneous vasoconstriction and impairs any cold-induced vasodilatation (CIVD) response. However, in the above studies (Daanen and van Ruiten, 2000;Mathew et al, 1977;1979;Takeoka et al, 1993;Purkayastha et al, 1999), the temperature of the digits prior to the local cold provocation was significantly lower in the hypoxic than in the normoxic cold test, despite the similar general thermal status of the subjects; this effect appears not to have been taken into account when concluding that hypoxia potentiates the cold-induced vasoconstrictor response. In view of the fact that the cold tests were performed a few hours (Daanen and van Ruiten, 2000;Mathew et al, 1977) or days (Daanen and van Ruiten, 2000;Mathew et al, 1977;1979;Takeoka et al, 1993;Purkayastha et al, 1999) after the arrival of the subjects at high altitude, the enhanced peripheral vasoconstrictor tone was probably attributable either to the distinct effects of hypoxia (Heistad and Wheeler, 1970;Kollai, 1983), or to the synergistic actions of hypoxia and low ambient temperature (Cipriano and Goldman, 1975).…”

Finger cold-induced vasodilation: a review

“…In particular, the onset time is shortened. The beneficial effect of vitamin C may be attributed to its antioxidant properties, metabolic and thermogenic properties, collagen synthesis, anti-stress activity and restoration of intercellular substances as well as to better maintenance of the rheological status of the blood (Purkayastha et al 1999).…”