Characterisation of NK receptors in guinea-pig urinary bladder smooth muscle: use of selective antagonists.

The aim of the present study was to characterise the neurokinin receptors involved in mediating contractile responses in guinea-pig urinary bladder smooth muscle. The use of selective NK1, NK2, and NK3 receptor agonists indicated that contractile responses in this tissue are mediated via activation of NK1 and NK2, but not NK3 receptors. This was confirmed by the observation that responses to [Sar9,Met(O2)11]substance P were inhibited by (+/-)-CP 96,345 (a NK1 receptor antagonist) and responses to eledoisin (following NK1 receptor desensitization) were inhibited by L-659,877 (a NK2 receptor antagonist).