Influence of Ascorbic Acid and of Thiamine on Physiological Responses of Guinea Pigs to High Ambient Temperature

Abstract

The effect of ascorbic acid and thiamine supplementation on response to chronic heat stress was measured in male guinea pigs. Chronic heat stress was associated with decreased food intake, weight loss, and decreased oxygen consumption. Colonic temperatures of heat-stressed guinea pigs remained above normal throughout the stress period. Total leukocyte and hemoglobin levels were significantly lower and eosinophil levels significantly higher in heat-stressed animals. Heart rates were not significantly different during early anesthesia. When body temperature fell to 36°C, heart rates were significantly less in heat-stressed animals. Necropsy indicated decreased liver weight to body weight ratios, decreased percentage of dry weight in adrenals, and increased percentage of dry weight in the livers of animals in the heat. No effect of vitamin supplementation on the physiological changes resulting from heat stress were found. Comparison with the effects of cold stress as reported in the literature indicates that heat and cold are dissimilar in their physiological effect on the guinea pig and that the response to vitamin supplementation is also dissimilar.