Pharmacological Study of Injected Cholinesterase

The aim of producing muscular relaxation during abdominal operations has been achieved with curare and other neuromuscular blocking agents, but unfortunately the use of such drugs is not always without risk, and the reversal of their action by neostigmine cannot be relied upon.The possibility was considered that cholinesterase in excess might inhibit the transmission of nervous impulses to the muscle.Its use would have the advantage that its paralytic action could be immediately nullified by the administration of anticholinesterase drugs.To the best of the author's knowledge, no experiments have been carried out to explore this possibility.If it could be proved that injected cholinesterase blocks neuromuscular trans- mission, another proof might also be established in favour of the theory of chemical transmission between nerve and muscle, although failure to produce such evidence would not invalidate this theory.Most of the work published on cholinesterase concerns the inhibition of its action by different drugs, and very few studies deal with the augmentation of the acetylcholine-hydrolysing capacity of the organism, which should follow the injection of cholinesterase.Mendel and Hawkins (1943) reported on the effects of injection into rats of horse serum pseudocholinesterase, dog pancreas pseudocholinesterase, and true cholinesterase prepared from the electric organ of the torpedo.They observed that the chromodacryorrhoea produced by subcutaneous injections of acetylcholine could be prevented if horse serum or dog pancreas pseudocholinesterase was injected intravenously before the administration of acetylcholine.Furthermore, they were able to show that these enzymes were not only capable of annulling the effects of injected acetylcholine but also that liberated at nerve synapses.They reached this conclusion on the basis that these enzymes interrupted the pupillary light reflexes.They obtained similar results in a few experiments with the true cholinesterase prepared from the electric organ of the torpedo.Recently Lesuk (1949) prepared a very potent true cholinesterase from bovine red blood cells.No pharmacological work on its action is known to the author apart from two recent short notes by Koppanyi and Karczmar (1948, 1949); their results will be referred to later.In this study Lesuk's preparation will be referred to as the