NAVAL AIR DEVELOPMENT CENTER WARMINSTERPA AVIATION MEDICAL ACCELERATION LAB
Stimulation of the rats reticulo-endothelial system RES was effective in enhancing the tolerances to high G acceleration stress. Utilizing 10 daily consecutive intraperitoneal injections of endotoxin at increasing doses from 100 to 1200 micro grams, the median survival time of 122 rats undergoing 20 positive G acceleration was increased from a control level of 9.7 min to 14.2 min. One group of 48 rats has a median survival of 23.6 min compared to a control level of 11.3 min. The protective action of RES stimulation and the inhibitory action of RES blockade was effective in rats with normal or prolonged survival but not in rats with diminished tolerance before stimulatinn or blockade. An analysis of factors for optimal RES stimulation is presented as are possible mechanisms of action.