Effects of exposure to 5°C and advancing age on tissue mast cells and heparin in male rats

¹ Department of Biochemistry and Nutrition, School of Medicine, and Laboratories of the Allan Hancock Foundation, University of Southern California, Los Angeles, California

Mast cell counts and heparin concentrations in liver, lung, kidney, thymus and spleen, and serum heparin levels and blood clotting times were determined in two age groups of male rats, exposed to 5°C for 1 week, and in controls of the same ages kept at room temperature. It was observed that the mast cell counts from different regions of the same organ were similar. With advancing age, the mast cells became more numerous in lung and thymus and, to a lesser degree, in kidney. Cold exposure caused an elevation of the mast cell numbers in the younger group but a depression in the older animals; these changes were significant in lung and thymus. The heparin content of thymus rose with advancing age; a similar trend was seen in lung. Cold exposure had no effect on tissue heparin levels. The serum concentration of the anticoagulant was not influenced by age or external temperature, but the clotting time was elevated by both advancing age and cold environment.