The effect of theophylline on the responses of the guinea-pig urinary bladder to nerve stimulation, adenosin 5' triphosphate and histamine.

The effects of theophylline (10(-5)M, 10(-4)M and 10(-3)M) on the contractile responses of the guinea-pig urinary bladder to nerve stimulation, adenosin 5' triphosphate (ATP) and histamine have been investigated. Contractile responses were unaffected by 10(-5)M and 10(-4)M therophylline but were significantly reduced by 10(-3)M theophylline. Since responses to histamine were reduced to a similar extent as responses to ATP, it is suggested that theophylline is not a specific antagonist of ATP in this tissue and that the ATP receptors in the bladder differ from those in other smooth muscle preparations.