BODANSKY: CHOLINESTERASE 



537 



a second group of 6, to a concentration of 27.1 micrograms per liter, 

 for 9 minutes; and 2 men, to 28.8 micrograms per liter, for 10 minutes, 

 40 seconds, and 27 micrograms per liter for 6 minutes, 20 seconds, re- 

 spectively. The symptoms were extremely mild. All of the men 

 showed miosis and most of them complained of a slight feeling of tight- 

 ness in the chest, lasting for several hours. The following symp- 

 toms were observed occasionally: increased nasal secretion, nausea, 

 salivation. 



Table 9 



Effect of Inh.alation of Diisopropyl-Fluorophosphate Vapor on Serum 

 Cholixesterase Activity In Vivo in Max 



* These values are per cent of the pre-exposure values 



Table 9 shows the decreases in serum cholinesterase activity, imme- 

 diately after exposure, and the rate of return of the activity to normal. 

 It may be seen that, immediately after gassing, the serum cholinesterase 

 activity decreased to about 1 to 5 per cent of the pre-exposure value. 

 The rate of return to normal was very slow. On the average, the activ- 

 ity returned to about 30 per cent, in four days; to about 50 per cent, in 

 8 days; and to about 70 per cent, in 15 days. The red cell cholin- 

 esterase activities of several of these men were determined immediately 

 after exposure and were found to be only slightly decreased below pre- 

 exposure values. These results show, therefore, a correlation with the 

 in vitro sensitivities of human serum and red cell activities. 



Rate of Restoration of Rabbit Plasma, Red Cell, and Brain Cholin- 

 esterase Activities after Poisoning with DFP. The slow rate of re- 

 generation of serum cholinesterase activities, demonstrated above in 

 man and monkey, raised the question as to the rate of regeneration of 

 brain cholinesterase activity. The average brain cholinesterase activ- 

 ity Vas first determined in a series of normal rabbits. Each of a group 



