Excitatory motor innervation in the canine rectoanal region: role of changing receptor populations.
Excitatory motor innervation in the canine rectoanal region: role of changing receptor populations.
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犬直肠肛门区域的兴奋性运动神经支配：受体群体变化的作用。
DOI：
10.1038/sj.bjp.0704987
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
Keef,KathleenD
中科院分区：
文献类型：
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作者：
Tichenor,StephenD;Buxton,IainLO;Johnson,Paul;O'Driscoll,Kate;Keef,KathleenD
犬直肠肛门区的运动神经支配是在环状肌层的分离条带中观察到的。对电刺激的收缩反应开始于肛门内括约肌，且持续时间长于直肠。对肛门内括约肌的运动神经支配几乎完全是交感神经，因为它被胍乙定(guan 3μM)阻断，而直肠近端的反应约50%是毒鼠碱的，对M3选择性拮抗剂4-二苯乙酰氧基-N-甲基哌啶(4-DAMP，0.1μM)和50%速激肽敏感，对神经激肽2(NK2)受体拮抗剂GR 94800(1μM)敏感。从IAS到直肠，内源性和外源性神经支配的相对贡献逐渐转移。对外源性递质的反应与观察到的运动神经支配的反应相似。IAS以去甲肾上腺素(NE)最强，直肠近端以乙酰胆碱(ACh)和NK-A最强。这些反应分别被哌唑嗪、4-DAMP和GR 94800抑制。通过测量[~3H]-哌唑嗪、[~3H]-奎宁基苯甲酸酯([~3H]-QNb)和[~3H]-SR-48968与平滑肌膜的结合，发现肾上腺素能α1、M胆碱和NK2受体的密度梯度也存在于直肠和直肠之间。DOI：10.1038/sj.bjp.0704987
Motor innervation in the canine rectoanal region was examined in isolated strips of the circular muscle layer. Contractile responses to electrical field stimulation began at lower frequencies and were more persistent in the internal anal sphincter (IAS) than in the rectum.Motor innervation to the IAS was almost exclusively sympathetic, since it was blocked by guanethidine (Guan 3 μM) while the response in the proximal rectum was approximately 50% muscarinic, and sensitive to the M3selective antagonist 4‐diphenylacetoxy‐N‐methylpiperidine (4‐DAMP, 0.1 μM) and 50% tachykinergic, and sensitive to the neurokinin 2 (NK2) receptor antagonist GR 94800 (1 μM). From IAS to rectum there was a gradual shift in the relative contribution of intrinsic and extrinsic neural innervation.Responses to exogenously applied transmitters exhibited a similar pattern to that observed with motor innervation. Norepinephrine (NE) was most potent in the IAS and acetylcholine (ACh) and NK‐A were most potent in the proximal rectum. The responses were inhibited by prazosin, 4‐DAMP and GR 94800 respectively.A gradient in the density of adrenergic α1, muscarinic and NK2receptors also existed from IAS to rectum as determined by measuring the binding of [3H]‐prazosin, [3H]‐quinuclidinyl benzilate ([3H]‐QNB and [3H]‐SR‐48968 to smooth muscle membranes.In summary, these data suggest that the shift in motor innervation in the rectoanal region is achieved in part by changes in receptor populations available for activation by sympathetic and enteric motor neurons.British Journal of Pharmacology(2002)137, 1321–1329. doi:10.1038/sj.bjp.0704987