REGENERATION OF ERYTHROCYTE AND BRAIN CHOLINESTERASE ACTIVITY IN RATS AFTER SUBLETHAL EXPOSURES TO GB VAPOR

¹ Chemical Corps Medical Laboratories, Army Chemical Center, Maryland

Rats were exposed daily to increasing concentration levels of GB vapor until severe toxic signs, such as convulsions, occurred. The animals showing these signs were used in following the regeneration of erythrocyte and brain ChE activities over a 60-day period after the last day of exposure. Immediately after exposure all convulsing animals showed erythrocyte ChE values below 10 per cent of normal and brain ChE values below 5 per cent of normal. Those not exhibiting toxic signs but similarly exposed had higher values. The brain did not show marked decrease in ChE activity until after the erythrocyte ChE activity was reduced to approximately 28 per cent of normal.

The rate of regeneration of ChE activity of erythrocytes was somewhat greater than that of the brain. For erythrocytes it was approximately 4.4 per cent per day for the first 15 days and thereafter was decreased to approximately 0.8 per cent per day. From these rates it was estimated that 48 ± 6 days (1 standard error) are required for complete recovery (100 per cent). Brain ChE activity followed a similar pattern, the rate being approximately 3.7 per cent per day for the first 15 days after which it was estimated to be 0.3 to 0.4 per cent per day. The time calculated for 100 per cent recovery was 140 ± 31 days.