Multiple Tachykinin Binding Sites in Hamster, Guinea-Pig and Rat Bladder

The tachykinin peptides are potent contractile agents in mammalian urinary bladder. This action appears to be mediated predominant1y by a direct action on smooth muscle since it is generally not altered by atropine, guanethidine, mepyramine or indomethacin [1,2]. As in other smooth muscle preparations, it has been suggested that there is more than one type of tachykinin receptor in mammalian bladder since PHYS is more potent than ELE or SP in rat, guinea-pig, and cat bladder whereas in hamster, mouse, dog, pig, monkey, and human bladder HE and KASS are substantially more potent than SP or PHYS. In view of the recent identification of three distinct types of tachykinin binding sites in the CNS and periphery that may be receptors for each of the three mammalian tachykinins, SP, SK, and NK, we have examined tachykinin binding sites in hamster, rat, and guinea-pig urinary bladder [see 3,4,5].