The Contractile Potency of Adenosine Triphosphate and Ecto-adenosine Triphosphatase Activity in Guinea Pig Detrusor and Detrusor From Patients With a Stable, Unstable or Obstructed Bladder

ABSTRACTPurpose: We compared the potency of adenosine triphosphate (ATP) and its nonhydrolyzable analogue α,β-methylene ATP for generating contractions in human detrusor smooth muscle from patients with a stable, unstable and obstructed bladders. The different ATP potencies were compared with the ecto-adenosine triphosphatase (ATPase) of these samples.Materials and Methods: Contractile experiments were done in vitro by superfusing samples with purines and dose-response curves were generated. Ecto-ATPase activity was measured from the rate of ATP hydrolysis sensitive to the ecto-ATPase inhibitor ARL 67156 with a luciferin-luciferase assay.Results: ATP generated contractions with a mean EC50 of 933 μM. in tissue from stable bladders and was significantly more potent in tissue from unstable and obstructed bladders (EC50 141 and 172 μM., respectively). α,β-methylene ATP was more potent in tissue from stable and unstable bladders (mean combined EC50 3 μM.). In guinea pig detrusor the mean EC50 for ATP and α,β-...