The effect of indomethacin and substance P on the guinea pig urinary bladder

Abstract The effects of indomethacin on the responses of the guinea pig urinary bladder to nerve stimulation, acetylcholine, adenosine 5′ triphosphate and Substance P have been investigated. Indomethacin alone had no significant effect on responses of the bladder to nerve stimulation but did significantly reduce the atropine-resistant contractions. Responses of the tissue to acetylcholine were unaffected by indomethacin but responses to Substance P were significantly reduced. Only the highest dose of ATP (10 −3 M) was significantly reduced by indomethacin. The possibility that Substance P is the transmitter responsible for the atropine-resistant contractions of the urinary bladder to nerve stimulation is discussed.