Cold treatment does not increase the rate of platelet clearance in 13‐lined ground squirrels.

Abstract

Thirteen‐lined ground squirrels (Spermophilus tridecemlineatus)experience a dramatic decrease in body temperature and heart rate during hibernation. These extreme conditions would likely cause human platelets to clot due to low blood flow rate and pressure. We have found that ground squirrels drastically decrease their circulating platelet and leukocyte counts during hibernation, likely to reduce the risk of clotting. Previous research has shown that chilled human and mouse platelets are rapidly cleared from circulation. However, upon arousal from torpor, ground squirrel platelets are rapidly released into circulation from their storage site in the spleen and persist for several days until new platelet synthesis begins. Flourescently labeled platelets were incubated at 4°C or 37°C and reinjected into autologous ground squirrels. Clearance rates of both warm and chilled platelets were the same. Identification of protective factors that prevent rapid clearance of chilled platelets may ultimately lead to the ability to refrigerate human platelet concentrates. This work was supported by an NIH R15 grant.