Sodium-potassium pump in guinea-pig parotid gland: secretagogue stimulation of ouabain binding to dispersed acini.
Sodium-potassium pump in guinea-pig parotid gland: secretagogue stimulation of ouabain binding to dispersed acini.
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豚鼠腮腺中的钠钾泵：促分泌剂刺激哇巴因与分散的腺泡结合。
DOI：
10.1113/jphysiol.1985.sp015607
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
Williams,JA
中科院分区：
文献类型：
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作者：
Hootman,SR;Williams,JA
从豚鼠腮腺中制备分散的腺泡，并在含有[3H]瓦巴因的HEPES缓冲林格（HR）液中于37℃孵育。Acini结合Na+‐K+‐泵抑制剂的平衡解离常数（Kd）估计为2.05微米，容量为2.9 X 10(6)个沃巴因结合位点/细胞。甲胆碱和肾上腺素分别使0.1微米的中等[3H]瓦阿因浓度达到的结合平衡水平增加了250%，但对10微米的中等瓦阿因浓度（糖苷接近饱和水平）的结合没有影响。这些结果表明，这两种促分泌剂引起Na+‐K+‐泵活性的增加，而不增加可用泵位点的数量。观察到的卡巴考的刺激很容易被阿托品逆转，肾上腺素引起的刺激被酚妥拉明逆转。在没有激动剂的情况下，acini与0.2 mM - EGTA在无Ca2+的HR中孵卵并没有改变[3H]瓦巴因的结合，但对碳乙醇和肾上腺素的反应降低了80%以上。在用激动剂刺激后，在无Ca2+的培养基中加入1.5 mM‐Ca2+可以恢复对两者的完全反应。在细胞外Ca2+存在或不存在的情况下，肾上腺素不能增强对最大有效剂量的碳醇的反应，反之亦然。碳巴酚和肾上腺素也刺激了230% ~ 260%的腺泡氧摄取的瓦阿因敏感成分，但对瓦阿因不敏感呼吸没有显著影响。在缺乏细胞外Ca2+的情况下，两种激动剂对氧摄取的刺激减少了80%以上，刺激作用在5分钟内消失。我们得出结论，0.1微米- [3H]瓦巴因结合平衡水平的变化和豚鼠腮腺腺对瓦巴因敏感氧摄取的变化都反映了腺泡Na+ - K+ -泵活性的变化。毒蕈碱胆碱能和α -肾上腺素能受体的占用以Ca2+依赖的方式强烈刺激泵活性。Na+ - K+泵是主要的能量需求离子运输组件，由这些分泌物激活。
Dispersed acini were prepared from guinea‐pig parotid glands and incubated at 37 degrees C in HEPES‐buffered Ringer (HR) containing [3H]ouabain. Acini bound the Na+‐K+‐pump inhibitor with an estimated equilibrium dissociation constant (Kd) of 2.05 microM and a capacity of 2.9 X 10(6) ouabain‐binding sites/cell. Carbachol and adrenaline each increased the equilibrium level of binding attained at a medium [3H]ouabain concentration of 0.1 microM by up to 250%, but had no effect on binding at a medium ouabain concentration of 10 microM, a near‐saturating level of the glycoside. These results indicate that the two secretagogues elicit increases in Na+‐K+‐pump activity without increasing the number of pump sites available. The observed stimulation by carbachol was readily reversed by atropine and that evoked by adrenaline was reversed by phentolamine. Incubation of acini in Ca2+‐free HR with 0.2 mM‐EGTA did not alter [3H]ouabain binding in the absence of agonists, but decreased by over 80% the response to both carbachol and adrenaline. The full response to either could be restored by adding 1.5 mM‐Ca2+ to the Ca2+‐free medium after challenge with agonists. The response to a maximally effective dose of carbachol could not be augmented by adrenaline or vice versa in either the presence or absence of extracellular Ca2+. Carbachol and adrenaline also stimulated the ouabain‐sensitive component of acinar oxygen uptake by 230‐260%, but had no significant effect on ouabain‐insensitive respiration. In the absence of extracellular Ca2+, stimulation of oxygen uptake by either agonist was reduced by over 80% and the stimulatory effects disappeared within 5 min. We conclude that alterations in equilibrium level of ouabain bound at 0.1 microM‐[3H]ouabain and in ouabain‐sensitive oxygen uptake by guinea‐pig parotid acini both reflect changes in acinar Na+‐K+‐pump activity. Muscarinic cholinergic and alpha‐adrenergic receptor occupancy strongly stimulates pump activity in a Ca2+‐dependent manner. Na+‐K+ pumps are the primary energy‐requiring ion‐transport component that is activated by these secretagogues.