The aim of the present study was to investigate the relaxatory function of adenosine receptor subtypes in rat urinary bladder, and if it is altered in the state of inflammation. The in vitro responses to the P1 receptor agonist adenosine were investigated in the presence of the general P2 receptor antagonist pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS; 1*10(-4) M).