The effects of ATP-receptor blocking agents on the response to the guinea-pig isolated bladder preparation to hyoscine-resistant nerve stimulation.

The effects of very high concentrations of quinidine, imidazole and phentolamine were investigated on the responses of the guinea-pig isolated bladder to nerve stimulation in the presence of hyoscine in an attempt to determine whether or not ATP mediated the contractions. Quinidine reduced the response to nerve stimulation without affecting the histamine controls, though this was probably due to a local anaesthetic effect. Imidazole potentiated the response to histamine. Phentolamine and two experimental drugs (2-2' pyridylisatogen and 2-2' methoxyphenylisatogen) that are active against ATP-induced relaxations of the guinea-pig isolated taenia were nonspecific in their blockade of the contractions of the bladder to nerve stimulation.