Up-regulation of bradykinin response in rat and human bladder smooth muscle.

Purpose: Responses to bradykinin were investigated in vitro in isolated control and hypertrophic smooth muscle strips from rat bladder.Materials and Methods: Bladder hypertrophy was induced by a 10-day period of partial urinary outflow obstruction. In addition, human bladder strips were also investigated.Results: Bradykinin (1 nM. to 1 μM.) caused contractions in all tissues studied. In the freshly isolated rat bladder preparations bradykinin induced contractions were similar and of small amplitude in control and hypertrophic tissues. After a 4-hour equilibratory period contractile responses to bradykinin and the B1 specific bradykinin receptor agonist desArg9 bradykinin were slightly increased in the controls but there was approximately a 6-fold increase in the hypertrophic muscle strips. After 4 hours of equilibration the human bladder strips showed a smaller but still significant increase in contractile response to bradykinin. Indomethacin, a cyclooxygenase inhibitor, almost abolished the increased res...