EFFECTS OF ADENOSINE 5'-TRIPHOSPHATE (ATP) AND BETA-GAMMA-METHYLENE ATP ON THE RAT URINARY-BLADDER

High concentrations of adenosine 5′‐triphosphate (ATP, 100 to 1000 μm) were required to cause contraction of the rat urinary bladder, while adenosine and adenosine 5′‐monophosphate (AMP, 1 to 50/im) produced relaxation. One hundred fold lower concentrations of β‐γ‐methylene ATP, which is resistant to degradation to AMP and adenosine, caused dose‐dependent, phasic contractions which mimicked atropine‐resistant responses to nerve stimulation. Adenosine and AMP caused dose‐dependent inhibition of carbachol‐induced contractions; theophylline competitively antagonized this inhibition but not the contractile responses to β‐γ‐methylene ATP, ATP or atropine‐resistant nerve stimulation. These results suggest that the insensitivity of the rat bladder to ATP is due to its rapid degradation to AMP and adenosine and support the hypothesis that the bladder receives a purinergic excitatory innervation. 1979 British Pharmacological Society