Mast cells,compound 48/80, and prolonged hypothermia in the rat

In the nonhibernating animal the stress of prolonged deep hypothermia is associated with the development of circulatory symptoms like those of burn-shock. Mast cells are sensitive to a variety of stressors, including thermal ones, and commonly react by releasing vasoactive substances that may facilitate vascular changes similar to those of burnshock. The possible role of mast cells in the complications of prolonged hypothermia was the object of this investigation. Two groups of female albino rats were subjected to 15° C total body hypothermia for 7.5 hr and then rewarmed artificially. Group I had been treated previously with compound 48/80 which depletes the mast cell content of tissues. Group II constituted controls and possessed a normal complement of mast cells. Progressive hemoconcentration was noted in both groups. However, the hematocrits of the 48/80-treated animals were significantly lower at selected intervals than those of control animals. In addition, 100% survival of the 48/80-treated animals was recorded in contrast to a 60% survival rate for controls. Microscopic examination of the mast cells in several tissues of additional controls suggested a loss of granule density during hypothermia and early rewarming. This investigation offers circumstantial evidence that mast cells of the rat facilitate the development of some of the deleterious effects of prolonged hypothermia.