Detail of "106128-89-6"

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Characterization of NK3 receptors in rabbit isolated iris sphincter muscle

Characterization of NK3 receptors in rabbit isolated iris sphincter muscle.Some chemicals with cas registry numbers like 106128-89-6 and 120814-48-4 are also used. Medhurst, Andrew D.; Parsons, Andrew A.; Roberts, Jennifer C.; Hay, Douglas W.P. (Department of Neurology Research, Essex CM19 5AW, UK). British Journal of Pharmacology, 120(1), 93-101 (English) 1997 Stockton. CODEN: BJPCBM. ISSN: 0007-1188. DOCUMENT TYPE: Journal CA Section: 2 (Mammalian Hormones) Tachykinin NK3 receptors were characterized in the rabbit isolated iris sphincter muscle by use of autoradiog. and in vitro functional studies. [125I]-[MePhe7]-neurokinin B (NKB) (1 nM), a selective NK3 receptor agonist, specifically labeled a population of NK3 receptors that were uniformly distributed throughout the rabbit iris sphincter muscle. This labeling was inhibited by unlabeled [MePhe7]-NKB (1 mM) but not by the NK1 receptor antagonist CP 99994 (1 mM). In the presence of CP 99994 (1 mM), the selective NK3 receptor agonists senktide and [Pro7]-NKB, and the natural preferred ligand for the NK3 receptor, NKB, were potent contractile agents in the rabbit iris sphincter muscle. They all produced monophasic concn.-effect curves with pD2 values of 9.53, 8.56 and 9.75, and nH values of 0.93, 1.53 and 0.76, resp. [MePhe7]-NKB was also a potent agonist, but produced shallow concn.-effect curves which appeared biphasic (nH=0.45). Contractile responses to senktide were surmountably antagonized in a concn.-dependent manner by the selective non-peptide NK3 receptor antagonist, SR 142801 (3-30 nM; pA2 = 8.9; slope = 0.99) and the non-peptide NK2/NK3 receptor antagonist, SR 48968 (3-30 mM; pA2 = 6.1; slope = 1.5). These pA2 values were consistent with functional rabbit NK3 receptors more closely resembling guinea pig and human NK3 receptors, than rat NK3 receptors. SR 142801 (10-100 nM) and SR 48968 (3 and 30 mM) inhibited responses to low (￡1 nM) but not higher (> 1 nM) concns. of [MePhe7]-NKB, and concn.-effect curves to [MePhe7]-NKB became steeper and monophasic in the presence of either antagonist. SR 142801 (3-30 nM) and SR 48968 (3-30 mM) also surmountably antagonized concn.-effect curves to [Pro7]-NKB and NKB, although results were more difficult to interpret, since the relationship between log concn.-ratios and the concn. of antagonist used did not adhere to the Schild equation. However, anal. of data with the lowest concn. of SR 142801 (3 nM) tested against NKB, and SR 48968 (3 mM) tested against [Pro7]-NKB and NKB, yielded apparent pA2 ests. of 9.3, 6.8 and 6.4, resp., consistent with blockade of NK3 receptors. SR 142801 (100 nM) had no effect on contractions induced by transmural nerve stimulation (2 Hz, 0.3 ms, 20 V for 30 s), whereas CP 99994 (1 mM) abolished these responses. Phenoxybenzamine pretreatment (20 mM, 10 min) markedly reduced max. responses to [MePhe7]-NKB (from 101% to 38% ref. contraction) and induced a marked (10 fold) rightward shift in the concn.-effect curve. The residual responses to [MePhe7]-NKB after phenoxybenzamine pretreatment were unaffected by 1 mM CP 99994 (max. response = 41%). These results demonstrate autoradiog. and functionally, the presence of NK3 receptors in rabbit iris sphincter muscle that mediate contractile responses to NK3 receptor agonists, but not to sensory trigeminal nerve stimulation. The present data with senktide and selective NK3 receptor antagonists suggest that functional rabbit NK3 receptors more closely resemble human and guinea pig NK3 receptors than rat NK3 receptors. However, the pharmacol. profiles of [MePhe7]-NKB, SR 142801 and SR 48968 suggest the presence of an "atypical" NK3 receptor or a heterogeneous population of NK3 receptors in this tissue. .

Characterization of tachykinin-induced ventral root depolarization in the neonatal rat isolated spinal cord

Characterization of tachykinin-induced ventral root depolarization in the neonatal rat isolated spinal cord. Ireland, S. J.; Wright, I. K.; Jordan, C. C. (Dep. Neuropharmacol., Glaxo Group Res. Ltd., Ware/Hertfordshire SG12 0DP, UK). Neuroscience (Oxford), 46(1), 217-23 (English) 1992. CODEN: NRSCDN. ISSN: 0306-4522. DOCUMENT TYPE: Journal CA Section: 2 (Mammalian Hormones) Depolarization responses to tachykinin receptor agonists were recorded extracellularly from lumbar ventral roots of spinal cord isolated from neonatal rats (1-8 days postpartum). All spinal cords were hemisected in the sagittal plane. In addn., in some hemisected cords, the dorsal horns were removed by means of a further cut, perpendicular to the first. In both hemisected and quadrisected spinal cords, reproducible depolarization responses were induced by low concns. of the neurokinin-1-selective agonist substance P methylester (10 nM-1 mM) or of the neurokinin-3-selective agonist senktide (3-300 nM). On both types of prepn., responses to substance P methylester (1 mM) or senktide (300 nM) were of comparable size. The amplitude of the response to senktide (300 nM) was reduced by at least 88% in spinal cord prepns. exposed to tetrodotoxin (0.5 mM0 or to physiol. medium contg. MgCl2 (20 mM). In contrast, under either of these conditions, concn.-response curves to substance P methylester were shifted rightward by 2. 76260-78-1 and 106128-89-6 which are cas registry numbers of chemicals are mentioned.8-8.5-fold, with little effect on the max. response. Responses to senktide were blocked selectively by the N-methyl-D-aspartate antagonist 3-[(±)-2-carboxypiperazine-4-yl]propyl-1-phosphonic acid (100 mM); the antagonist had little effect on substance P methylester-induced depolarization (mean concn. ratio 2.0). These results suggest that in the neonatal rat spinal cord, application of exogenous tachykinin agonists can induce ventral root depolarization by activation of neurokinin-1 and/or neurokinin-3 receptors. The response to stimulation of neurokinin-1 receptors has a major component likely to be due to a direct action at motoneurons. In contrast, ventral root depolarization evoked by stimulation of neurokinin-3 receptors is due, almost exclusively, to an indirect action. The observation that depolarization-induced by the neurokinin-3 agonist senktide was not abolished by removal of the dorsal horns is at variance with the finding that in the adult rat, neurokinin-3 binding sites are confined to this region of the spinal cord. .