EFFECTS OF ADENOSINE 5′‐TRIPHOSPHATE (ATP) AND β‐γ‐METHYLENE ATP ON THE RAT URINARY BLADDER

Abstract

1 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. 2 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. 3 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. 4 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.