Protective Effect of Acetyl-Beta-Methylcholine, Carbamylcholine and Atropine on X-Irradiated Mice

Abstract

A decrease in the radiation-induced mortality of C57 BL mice was obtained by the intraperit. injn. of acetyl-beta-methylcholine bromide (Mecholyl bromide 8-135 mg./kg. body wt.), acetyl-beta-methylcholine chloride (Mecholyl chloride 36 mg./kg.) or carbamylcholine (Doryl 1 mg./kg.) 3-5 min. before 600-1000 r of X-rays. Protection appeared to be more or less independent of inherent sensitivity, the decrease in mortality corresponding to 200-300 r of X-rays in all age groups. Testicular atrophy and depigmentation of fur in the surviving mice indicated that the protection against injury was only partial and that recovery was not complete. Earlier recovery was observed in the "protected" mice. Atropine cancelled the protective action of the parasym-pathomimetic drugs and also failed to decrease the mortality of mice when given alone 3-5 min. before or 1-3 min. following 800 r of X-rays. Evidence currently available points toward drug-induced hypoxia as the most likely mechanism by which Mecholyl and Doryl exerted their protective action.