EFFECTS OF SELECTED ORGANOPHOSPHATE INSECTICIDES ON SERUM-CHOLINESTERASE ISOENZYME PATTERNS IN THE RAT

The serum cholinesterase (ChE) isoenzyme in rats shows 6 bands after p olyacrylamide gradient gel electrophoresis. The effects of organophosp hates (fenthion, chlorpyrifos, diazinon, bromophos, propaphos, haloxon , and DFP) on serum ChE isoenzyme bands were studied in 32 male and 32 female 6-w-old Sprague-Dawley rats. Each organophosphate was randomly administered to 4 male and 4 female rats. Blood samples were collecte d from the abdominal aorta under halothane anesthesia 6 h after dosing . The isoenzyme patterns were determined simultaneously with erythrocy te and serum ChE activities. Changes were observed in all 6 bands of t he serum ChE isoenzymes after administration of fenthion, chlorpyrifos and propaphos. Diazinon had no influence on band 6, and DFP and bromo phos had no influence on band 5. Haloxon did not effect any of the ser um ChE isoenzyme bands. Serum ChE was most suppressed by fenthion, fol lowed by DFP, bromophos, chlorpyrifos, propaphos and diazinon in that order of effect. Serum ChE activity was not suppressed by haloxon. Ery throcyte ChE activity was suppressed by every organophosphate. This ex periment demonstrated a correlation between the organophosphate suppre ssion of serum ChE activity and the concentration of serum ChE isoenzy me band 6.