Plasma cholinesterase activity of rats, western grey kangaroos, alpacas, sheep, cattle, and horses.

Introduction: Plasma cholinesterase activity levels of various species may be of interest to toxicologists or pathologists working with chemicals that interfere with the activity of plasma cholinesterase.

Methods: We used a pH titration method to measure the plasma cholinesterase activity of six mammalian species.

Results: Plasma cholinesterase activity varied up to 50-fold between species: sheep (88 ± 45 nM acetylcholine degraded per ml of test plasma per minute), cattle (94 ± 35), western grey kangaroos (126 ± 92), alpaca (364 ± 70), rats (390 ± 118) and horses (4539 ± 721).

Discussion: We present a simple, effective technique for the assay of plasma cholinesterase activity levels from a range of species. Although labour-intensive, it requires only basic laboratory equipment.