The effect of troxypyrrolidinium, a choline uptake inhibitor, on the excitatory innervation of the rat urinary bladder.

Troxypyrrolidinium, a choline uptake inhibitor, reduced but failed to abolish responses of the rat urinary bladder to electrical stimulation at 1-100 Hz although it reduced acetylcholine output during stimulation at 10 Hz to a level similar to that of spontaneous release. Inhibition of the response to stimulation was more complete at faster rates of stimulation and was partially reversed by choline. Troxypyrrolidinium produced a greater inhibition of the 'tonic' component of the response to electrical stimulation than of the 'phasic' component. Hemicholinium-3 or hyoscine produced a similar selective effect on the 'tonic' component. Hemicholinium-3 also reduced acetylcholine output during electrical stimulation to a similar extent as troxypyrrolidinium but hyoscine increased transmitter output. The results support the concept of a second transmitter in the excitatory innervation of the bladder.