Comparison of two substrates in determination of plasma cholinesterase activity & genetic variability.

Two substrates, acetyl thiocholine iodide ATCI and benzoylcholine chloride BCC were compared for the determination of plasma cholinesterase ChE levels and after incorporation of dibucaine and sodium fluoride in the assay, their usefulness in determining plasma ChE genetic variability was assessed in 64 healthy subjects. With both substrates, plasma ChE levels were found to be in the reference range. However, ATCI could detect only two variants with the usual phenotype UU in 60 of 64 [93.75%] subjects whereas with BCC 6 different groups could be determined. Though both substrates are of equal value in estimation of plasma ChE levels, BCC is definitely superior in determining its genetic variants.

Comparison of Pseudocholinesterase Activity between Nonpregnant and Term-pregnant Women with the Genotypically Normal Enzyme / 대한마취과학회지

BACKGROUND: Many reports on the change of pseudocholinesterase activity in pregnant women showed that it declines during pregnancy and in the immediate postpartum period. In Korea, there are two papers that show dissident results. However, they didn't prove that the subjects in their studies had genotypically normal enzyme. So, we compared the pseudocholinesterase activities between nonpregnant and term-pregnant women who have the genotypically normal enzyme. METHODS: We measured the dibucaine, fluoride, chloride number as well as the pseudocholinesterase astivity using butyrylthiocholine as substrate by automatic analyser, urea and scoline numbers using benzoylcholine as substrate by manual technique in nonpregnant(n=15) and term-pregnant(n=15) women aging 20 to 40 years old before induction of anesthesia. RESULTS: The dibucaine, fluoride, chloride, urea and scoline numbers(mean+/-SD,%) in female subjects were 86+/-1.2, 50+/-5.2, 5+/-2.4, 47+/-2.8 and 92+/-2.0, respectively. There were two subjects showing low pseudocholinesterase activity(<4.8 U/ml) and the one(3.9 U/ml) was in nonpregnant group, the other(4.5 U/ml) in term-pregnant group. We found that they had genotypically normal enzymes because their inhibition numbers were within normal ranges. Pseudocholinesterase activity(mean+/-SD) in term-pregnant group(7.04+/-1.30) was significantly decreased compared with that in nonpregnant group(9.15+/-2.01)(P<0.01). CONCLUSIONS: We conclude that in subjects with the genotypically normal enzyme, term-pregnant women had significantly lower pseudocholinesterase activity than nonpregnant ones did.