As reported previously, the beta-adrenoceptor-evoked response in the in vitro rabbit detrusor is inhibited by non-steroidal anti-inflammatory drugs (NSAIDs). Prostaglandins can restore this response. This study was designed to better define physiological influences on beta-adrenoceptors in the urinary bladder and to ascertain whether the observations made in the rabbit urinary bladder in vitro were valid in vivo, as well as in a different animal species, i.e. in the rat. The NSAID indometacin partially inhibited the isoproterenol-evoked response in the rat detrusor muscle. When the neurokinin A (NKA) antagonist MEN-10376 was administered after indometacin, the beta-adrenoceptor-evoked response was completely abolished. The isoproterenol-evoked beta response was dose dependently reduced following treatment with the capsaicin antagonist ruthenium red. Taken together, these data indicate an involvement of prostanoids, NKA- and capsaicin-sensitive fibres in the beta-adrenoceptor-evoked response in the rat urinary bladder.