Effects of noradrenaline on intracellular pH in acutely dissociated adult rat hippocampal CA1 neurones
Effects of noradrenaline on intracellular pH in acutely dissociated adult rat hippocampal CA1 neurones
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去甲肾上腺素对急性分离成年大鼠海马 CA1 神经元细胞内 pH 值的影响
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
J. Church
中科院分区：
文献类型：
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作者：
Garth A. M. Smith;C. Brett;J. Church
1我们研究了去甲肾上腺素对稳态细胞内pH（pHi）的影响，以及通过NH 4+预脉冲技术在成年大鼠海马CA 1神经元中急性分离的内酸负荷中pHi的恢复。[2]在名义上无HCO 3 −的条件下，酸排出是通过Na+依赖性机制完成的，可能是先前在胎儿和成年大鼠海马神经元中表征的Na+-H+交换体的阿米洛利不敏感变体。在存在外部HCO 3 −的情况下，酸挤出似乎得到了Na+-依赖性HCO 3 −-Cl−交换剂的补充，其活性取决于pHi的绝对水平。3去甲肾上腺素引起稳态pHi的浓度依赖性和持续升高，并增加细胞内酸负荷的pHi恢复率。去甲肾上腺素的作用不依赖于外部HCO 3 −的存在，但通过用N-甲基-D-葡糖胺替代外部Na+而被阻断，这表明去甲肾上腺素通过增加Na+-H+交换剂的活性来增加稳态pHi。4去甲肾上腺素对稳态pHi和从施加的酸负荷中恢复pHi的速率的影响被β1-和β2-肾上腺素受体激动剂模拟，但不是α-肾上腺素受体激动剂。β肾上腺素受体拮抗剂普萘洛尔阻断去甲肾上腺素增加稳态pHi和从酸负荷中恢复pHi的能力。5去甲肾上腺素对稳态pHi和酸负荷后pHi恢复率的影响不依赖于[Ca 2 +]i的变化。然而，去甲肾上腺素的作用可通过腺苷酸环化酶抑制剂2′，5 ′-二脱氧腺苷和cAMP依赖性蛋白激酶抑制剂Rp-腺苷-3 ′，5 ′-环硫代磷酸（钠盐; Rp-cAMPS）和N-[2-（对溴肉桂氨基）乙基]-5-异喹啉磺酰胺（H-89）预处理阻断。6内源性腺苷酸环化酶激活剂Forskolin和磷酸二酯酶抑制剂3-异丁基-1-甲基黄嘌呤模拟了去甲肾上腺素增加稳态pHi和从施加的酸负荷中恢复pHi的速率的能力，就像Sp-cAMPS一样，cAMP依赖性蛋白激酶的选择性激活剂。毛喉素对稳态pHi的影响被Rp-cAMPS预处理阻断，而Sp-cAMPS的作用被蛋白磷酸酶抑制剂冈田酸预处理增强。7去甲肾上腺素还增加了培养的出生后大鼠海马神经元的稳态pHi和从施加的酸负荷中恢复的pHi速率。在该制剂中，通过用霍乱毒素预处理18-24 h阻断去甲肾上腺素的作用。8我们得出结论，去甲肾上腺素增加了大鼠海马神经元中Na+-H+交换体的活性，可能是通过诱导反向转运的pHi依赖性的碱性转变，从而提高稳态pHi。去甲肾上腺素的作用由β-肾上腺素受体介导，途径涉及刺激性G蛋白Gs（Gsα）的α-亚基、腺苷酸环化酶、cAMP和随后的cAMP依赖性蛋白激酶活化，后者反过来可能使交换机制磷酸化。
1 We examined the effects of noradrenaline on steady‐state intracellular pH (pHi) and the recovery of pHi from internal acid loads imposed by the NH4+ prepulse technique in hippocampal CA1 neurones acutely dissociated from adult rats. 2 Under nominally HCO3−‐free conditions, acid extrusion was accomplished by a Na+‐dependent mechanism, probably the amiloride‐insensitive variant of the Na+‐H+ exchanger previously characterized in both fetal and adult rat hippocampal neurones. In the presence of external HCO3−, acid extrusion appeared to be supplemented by a Na+‐dependent HCO3−‐Cl− exchanger, the activity of which was dependent upon the absolute level of pHi. 3 Noradrenaline evoked a concentration‐dependent and sustained rise in steady‐state pHi and increased rates of pHi recovery from imposed intracellular acid loads. The effects of noradrenaline were not dependent upon the presence of external HCO3− but were blocked by substituting external Na+ with N‐methyl‐D‐glucamine, suggesting that noradrenaline acts to increase steady‐state pHi by increasing the activity of the Na+‐H+ exchanger. 4 The effects of noradrenaline on steady‐state pHi and on rates of pHi recovery from imposed acid loads were mimicked by β1‐ and β2‐, but not α‐, adrenoceptor agonists. The β‐adrenoceptor antagonist propranolol blocked the ability of noradrenaline to increase both steady‐state pHi and rates of pHi recovery from acid loads. 5 The effects of noradrenaline on steady‐state pHi and on pHi recovery rates following acid loads were not dependent on changes in [Ca2+]i. However, the effects of noradrenaline were blocked by pre‐treatment with the adenylate cyclase inhibitor 2′,5′‐dideoxyadenosine and the cAMP‐dependent protein kinase inhibitors Rp‐adenosine‐3′,5′‐cyclic monophosphorothioate (sodium salt; Rp‐cAMPS) and N‐[2‐(p‐bromocinnamylamino)ethyl]‐5‐isoquinolinesulphonamide (H‐89). 6 Forskolin, an activator of endogenous adenylate cyclase, and 3‐isobutyl‐1‐methylxanthine, a phosphodiesterase inhibitor, mimicked the ability of noradrenaline to increase both steady‐state pHi and rates of pHi recovery from imposed acid loads, as did Sp‐cAMPS, a selective activator of cAMP‐dependent protein kinase. The effect of forskolin on steady‐state pHi was blocked by pre‐treatment with Rp‐cAMPS whereas the effect of Sp‐cAMPS was enhanced by pre‐treatment with the protein phosphatase inhibitor, okadaic acid. 7 Noradrenaline also increased steady‐state pHi and rates of pHi recovery from imposed acid loads in cultured postnatal rat hippocampal neurones. In this preparation, the effects of noradrenaline were occluded by 18–24 h pre‐treatment with cholera toxin. 8 We conclude that noradrenaline increases the activity of the Na+‐H+ exchanger in rat hippocampal neurones, probably by inducing an alkaline shift in the pHi dependence of the antiport, thereby raising steady‐state pHi. The effects of noradrenaline are mediated by β‐adrenoceptors via a pathway which involves the α‐subunit of the stimulatory G‐protein Gs (Gsα), adenylate cyclase, cAMP and the subsequent activation of cAMP‐dependent protein kinase which, in turn, may phosphorylate the exchange mechanism.
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影响因子：
2.5
作者：
Sanchez-Armass,S;Martinez-Zaguilan,R;Martinez,GM;Gillies,RJ
通讯作者：
Gillies,RJ
影响因子：
3.6
作者：
John Church;Elizabeth J. Fletcher;K. Abdel‐Hamid;J. F. MacDonald
通讯作者：
John Church;Elizabeth J. Fletcher;K. Abdel‐Hamid;J. F. MacDonald
通过阿米洛利不敏感的 Na /H 交换器调节培养的海马神经元的细胞内 pH 值。
DOI：
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发表时间：
1991
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Raley-Susman,KM;CragoeJr,EJ;Sapolsky,RM;Kopito,RR
通讯作者：
Kopito,RR
G α 13 刺激 Na-H 交换。
DOI：
--
发表时间：
1994
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Voyno-Yasenetskaya,T;Conklin,BR;Gilbert,RL;Hooley,R;Bourne,HR;Barber,DL
通讯作者：
Barber,DL
DOI：
10.1073/pnas.93.22.12631
发表时间：
1996-10-29
影响因子：
11.1
作者：
Lin, X;Barber, DL
通讯作者：
Barber, DL