Effects of non-depolarizing neuromuscular blocking agents on the cardiac vagus nerve in the guineapig.

The ability of gallamine, metocurine, pancuronium, tubocurarine and atropine to block the response to postganglionic stimulation of the vagus nerve were measured in isolated, spontaneously beating guineapig atria. From analysis of the results in conjunction with those of earlier assays of concentrations that block effects of preganglionic vagal stimulation, it was concluded that only tubocurarine possessed ganglionic blocking activity. From calculation of the extent of block of muscarinic receptors at drug concentrations which blocked the response to postganglionic vagal stimulation, it was concluded that gallamine and pancuronium have an antivagal action exerted most probably on the postganglionic nerve terminal, and that this action is the most likely explanation of the tachycardia seen clinically with these two drugs.