The effect of indomethacin and adenosine 5'-triphosphate on the excitatory innervation of the rate urinary bladder.

Adenosine 5'-triphosphate (ATP) (20-400 microM) contracted 48% of isolated rat urinary bladder preparations but induced no response in the remainder. The response to ATP never exceeded 25% of the response to electrical stimulation in the presence of indomethacin (50 microM) plus hyoscine (25 microM) and usually developed more slowly than that to electrical stimulation. Autoinhibition could be produced to ATP by incubating the tissue with ATP (200 microM) for 20 min. Incubation of the tissue with ATP (200 microM) for 60 min in the presence of indomethacin (50 microM) and either hyoscine (25 microM) or hemicholinium-3 (500 microM) reduced but failed to abolish responses to electrical stimulation. Responses to acetylcholine were not affected by ATP (200 microM) in the presence of indomethacin and the output of acetylcholine induced by neuronal stimulation at 10 Hz was not inhibited by ATP (200 microM) or by indomethacin (50 microM). The results suggest a possible modulatory role for ATP in the excitatory innervation of the rat urinary bladder.