Assessment of muscarinic receptor subtypes in human and rat lower urinary tract by tissue segment binding assay
Assessment of muscarinic receptor subtypes in human and rat lower urinary tract by tissue segment binding assay
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DOI：
10.1254/jphs.fp0071435
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发表时间：
2008-02-01
影响因子：
3.5
通讯作者：
Muramatsu, Ikunobu
中科院分区：
文献类型：
--
作者：
Anisuzzaman, Abu Syed Md;Morishima, Shigeru;Muramatsu, Ikunobu
采用两种放射性配体的完整组织段结合法对人和大鼠下尿路（膀胱逼尿肌、粘膜和前列腺）中的毒蕈碱受体进行了鉴定，并观察了受体在体外长期活化对毒蕈碱受体的影响。亲水的[H-3]-NMS与疏水的[H-3]-QNB以相同的密度结合在逼尿肌节段，提示毒碱受体定位于质膜。虽然逼尿肌中的毒蕈碱受体密度高于膀胱粘膜和前列腺，但在密度和亚型分布上（逼尿肌中的M-1、M-2和M-3亚型，膀胱粘膜中的M-2和M-3亚型，前列腺中的M-1和M-2亚型）均无物种特异性差异。逼尿肌条与氯乙醇孵育20分钟后，[(3)H]-NMS结合位点减少，60分钟后，[(3)H]-QNB结合位点减少。两种放射性配体在碳二醇处理后3小时内结合位点的损失是相同的（约40%）。完整的组织片段结合试验揭示了不同毒毒碱受体亚型在人和大鼠下尿路的组织特异性和质膜分布及其动态变化（内化和下调）。
Muscarinic receptors in the human and rat lower urinary tract (urinary bladder detrusor muscle and mucosa, and prostate) were identified by intact tissue segment binding assays with two radioligands, and the effects of prolonged receptor activation in vitro on muscarinic receptors were examined. Hydrophilic [H-3]-NMS and hydrophobic [H-3]-QNB bound to the detrusor muscle segments with the same density, suggesting that the muscarinic receptors were localized at the plasma membrane. While the density of muscarinic receptor was higher in detrusor muscle than in the bladder mucosa and prostate, there was no species-specific difference either in density or in subtype distribution (M-1, M-2, and M-3 subtypes in detrusor; M-2 and M-3 subtypes in bladder mucosa; and M-1 and M-2 subtypes in prostate). Incubation of detrusor strips with carbachol decreased [(3) H]-NMS binding sites within 20 min, followed by a reduction of [(3) H]-QNB binding sites after a 60-min lag phase. The loss of the binding sites over 3 h after carbachol treatment was the same (approximately 40%) for both radioligands. The present intact tissue segment binding assay reveals tissue-specific and plasma membrane distribution of distinct muscarinic receptor subtypes and their dynamic changes (internalization and down-regulation) in lower urinary tract of humans and rats.