Characterization of cholinergic muscarinic receptors in cow tracheal muscle membranes. Effect of maturation.
Characterization of cholinergic muscarinic receptors in cow tracheal muscle membranes. Effect of maturation.
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牛气管肌膜中胆碱能毒蕈碱受体的表征。
DOI：
10.1016/0006-2952(87)90055-4
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发表时间：
1987
影响因子：
5.8
通讯作者：
Douglas,JS
中科院分区：
文献类型：
--
作者：
Rothberg,KG;Morris,PL;Douglas,JS
副交感神经系统在控制基底气道肌张力和口径中起重要作用。我们在离体气管中鉴定了毒蕈碱胆碱能受体！使用l-[3h]苯基喹啉酯（l-[3h] QNB）作为放射性配体，从三个年龄组奶牛（未成熟，< 2周龄；过渡期，3 - 5个月；成熟期，50 - 5年）的膜中提取。成熟后，l [3h] QNB结合位点的密度显著降低（未成熟奶牛、过渡奶牛和成熟奶牛的最大B值分别为2344±169、1381±85和1116±80 mol/mg）。未成熟、过渡和成熟动物组织的解离常数没有变化（K d分别为0.38±0.09 nM和0.55±0.06 nM和0.50±0.07 nM）。结合力和解离速率常数在未成熟动物和成熟动物的组织之间没有变化。乙酰胆碱酯酶的比活性与气管匀浆中l-[3h] QNB结合位点的密度相关；也就是说，随着成熟，未成熟、过渡和成熟动物组织中乙酰胆碱酯酶活性显著降低[分别为0.28±0.01 vs 0.16±0.02 vs 0.08±0.01 mol·1−1·min−1·（mg蛋白）−1]。所有使用毒蕈碱拮抗剂的竞争结合研究都显示单位点结合，并且在年龄组之间没有显示药物亲和力的任何差异。相反，与甲胆碱、甲胆碱和毒蕈碱存在多个结合位点，毒蕈碱激动剂的受体亲和力显著降低。高亲和力位点和低亲和力位点的比例没有变化。这些结果表明，随着成熟，气管平滑肌中毒蕈碱受体的性质发生了变化。
The parasympathetic nervous system is important in the control of basal airway muscle tone and caliber. We characterized muscarinic cholinergic receptors in isolated trachea! membranes from cows of three age groups (immature,< 2 weeks; transition, 3–5 months; and mature,> 5 years) using l-[3 H] quinuclidinyl benzilate (l-[3 H] QNB) as the radioligand. There were significant decreases in the densities of l [3 H] QNB binding sites with maturation (B max: 2344±169 vs 1381±85 vs 1116±80 mol/mg protein for tissues from immature, transition and mature cows respectively). No change in the dissociation constant was observed with maturation (K d: 0.38±0.09 vs 0.55±0.06 vs 0.50±0.07 nM for tissues from immature, transition and mature animals respectively). The association and dissociation rate constants did not vary between tissues from immature and mature animals. The specific activity of the enzyme, acetylcholinesterase, was correlated with the density of l-[3 H] QNB binding sites present in the tracheal homogenates; that is, with maturation, there were significant decreases in acetyl-cholinesterase activity [0.28±0.01 vs 0.16±0.02 vs 0.08±0.01 mol· 1− 1· min− 1·(mg protein)− 1 for tissues from immature, transition and mature animals respectively]. All competition binding studies using muscarinic antagonists exhibited single site binding and did not show any differences in drug affinities between the age groups. In contrast, multiple binding sites were observed with carbachol, methacholine and muscarine, and there were significant decreases in receptor affinities for the muscarinic agonists. No changes in the proportion of high and low affinity sites were found. These results indicate that with maturation there are alterations in the properties of muscarinic receptors in tracheal smooth muscle.