Effects of alverine citrate on cat intestinal mechanoreceptor responses tochemical and mechanical stimuli

Background: Alverine citrate is commonly used in the treatment of painful a ffections of the colon. Aim: To determine whether alverine citrate acts on the vagal sensory ending s. Methods: Unitary recordings were performed at the level of the vagal fibres in the nodose ganglion of anaesthetized cats using extracellular glass mic roelectrodes, and the patterns of response to chemical and mechanical stimu li applied to identified vagal intestinal mechanoreceptors were studied. Results: The intestinal mechanoreceptors located at the endings of type C v agal fibres responded mainly to mechanical stimuli (distension and contract ion), but also responded to chemical substances (cholecystokinin and substa nce P), The most conspicuous effect of alverine (2 mg/kg) was that it signi ficantly inhibited the pattern of vagal activity produced in response to ei ther cholecystokinin (5-10 mu g/kg), substance P (5-10 mu g/kg) or phenylbi guanide (5-10 mu g/kg), a 5-HT3 receptor agonist, On the other hand, the un itary vagal response to the mechanical distension was slightly enhanced by alverine, as was any spontaneous activity present. Conclusions: Based on the present data, alverine citrate can be said to dec rease the sensitivity of the intestinal mechanoreceptors, which is consiste nt with its previously established anti-spasmodic effects.