Hematological changes in deer mice acclimated at different ambient temperatures

¹ Department of Zoology, University of Arkansas, Fayetteville, Arkansas

Deer mice (Peromyscus maniculatus and Peromyscus leucopus) were acclimated at temperatures of 5° ±0.5°C and 30°±0.5°C for various intervals with periods at 20°±0.5°C preceding the cold and warm acclimation periods. Hemoglobin concentrations, hematocrits and erythrocyte diameters were measured on a group of nonsplenectomized mice and on another group of splenectomized mice which were subjected to similar temperature conditions. It was found that there were significant increases in hemoglobin and hematocrit values with acclimation at 5°C, which were more marked in the splenectomized mice. Differences in hemoglobin concentrations and hematocrits were significant between 5° and 30°C, but differences were not as apparent between mice at 30°C and those exposed at 20°C. There were no significant changes in erythrocyte diameters, although the mean corpuscular hemoglobin concentration was significantly lower in all of the splenectomized mice as opposed to the nonsplenectomized ones. It is suggested that splenectomy in some way enhances erythopoiesis in response to low temperature since there was no significant difference in hematocrits of nonsplenectomized and splenectomized mice exposed at 20°C prior to cold acclimation.