Canadian Journal of Anesthesia, Vol 33, 321-327, Copyright © 1986 by Canadian Anesthesiologists' Society

Shortened Action of Succinylcholine in Individuals with Cholinesterase C₅ Isozyme

¹ Department of Anesthesiology, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama-shi, 930-01, Japan

To test the possibility that individuals with and without plasma cholinesterase C₅ isozyme have differences in neuromuscular sensitivity to succinylcholine chloride, we examined the effects of succinylcholine in these two groups of patients. Sera from 491 adult patients were examined for presence of the plasma cholinesterase C₅ isozyme by use of electrophoresis with polyacrylamide; 24 were positive for the C₅ isozyme. Plasma cholinesterase activity and duration of action of succinylcholine were measured in 12 C₅ positive patients and 18 C₅ negative patients, all of whom had the normal cholinesterase genotype. C₅ positive patients had 30.1 per cent higher mean plasma cholinesterase activity than C₅ negative patients. The duration of neuromuscular blockade, measured by the first twitch height evoked by train-of-four stimulation, was significantly shorter in C₅ positive patients than C₅ negative patients. The C₅ positive individuals had shorter duration of action of succinylcholine than C₅ negative individuals.

Key Words: ENZYMES: cholinesterases, isoenzyme • NEUROMUSCULAR RELAXANTS: succinylcholine • TECHNIQUES: electrophoresis, polyacrylamide gel