Y. Torrens et al., INVOLVEMENT OF SEPTIDE-SENSITIVE TACHYKININ RECEPTORS IN INOSITOL PHOSPHOLIPID HYDROLYSIS IN THE RAT URINARY-BLADDER, Peptides, 16(4), 1995, pp. 587-594
The selective NK? agonist [Lys(5),MeLeu(9),Nle(10)]NKA(4-10) markedly
stimulated [H-3]inositol monophosphate (IPI) formation in prisms from
the rat urinary bladder. This response was blocked by the NK, antagoni
st SR 48968. Senktide (NK, agonist) was inactive. Septide, a short SP
analogue, and the NK1 agonists [Pro(9)]SP and [Sar(9)]Met(O-2)(11)]SP
also stimulated [H-3]IP1 formation and several NKI tachykinin antagoni
sts (RP 67580, CP 96345, GR 82334, and [D-Pro(9), t beta-BPr10,Trp(11)
]SP) were more potent in blocking the septide than the [Pro(9)]SP resp
onse. GR 82334 was the most discriminative. SR 48968 (10(-6) M) shifte
d the [Pro(9)]SP dose-response curve but did not modify the septide do
se-response curve. Septide had a low affinity for [H-3][Pro(9)]SP bind
ing sites, suggesting further that septide and NKI agonists act on dif
ferent receptors. Finally, both [Pro(9)]SP and [Sar(9),Met(O-2)(11)]SP
blocked the septide-evoked response, acting as partial agonists at th
e septide-sensitive tachykinin receptors.