Red blood cell cholinesterase

Inhibition of the two principal human cholinesterases, acetylcholinesterase and pseudocholinesterase, may not always result in visible neurological effects (Sundlof et al. 1984). Acetylcholinesterase, also referred to as true cholinesterase, red blood cell cholinesterase, or erythrocyte cholinesterase is found in erythrocytes, lymphocytes, and at nerve synapses (Goldfrank et al. 1990). Inhibition of erythrocyte or lymphocyte acetylcholinesterase is theoretically a reflection of the degree of synaptic cholinesterase inhibition in nervous tissue, and therefore a more accurate indicator than pseudocholinesterase activity of inhibited nervous tissue acetylcholinesterase (Fitzgerald and Costa 1993 Sundlof et al. 1984). Pseudocholinesterase (also referred to as cholinesterase, butyrylcholinesterase, serum cholinesterase, or plasma cholinesterase) is found in the plasma, serum, pancreas, brain, and liver and is an indicator of exposure to a cholinesterase inhibitor. 

Summary Methamidophos given in the diet for periods of one or two years, resulted in body weight loss in the rat and mouse, but not the dog. There was an increase in relative brain weight at the highest dose tested (HDT) in these rodents, in both sexes, but not in the dog. There were few clinical signs and no evidence of oncogenicity. In all three species, inhibition of AChE in plasma (which also includes butyryl cholinesterase), red blood cell (RBC) and brain was reported. The LOEL for inhibition of brain AChE was 2 ppm, equivalent to 0.1, 0.3 or 0.06 mg/kg/day in the rat, mouse and dog, respectively. An estimated NOEL of 0.02 mg/kg/day, after 11-18% inhibition of brain AChE at 0.06 mg/kg/d in a 1-yr. dog study, was the critical one selected for chronic risk characterization. The use of an uncertainty factor of 3 (rather than 10) in calculating an estimated NOEL from a LOEL was supported by Benchmark Dose (BMD) calculations. 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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