Intracellular pH response to hypercapnia in neurons from chemosensitive areas of the medulla.
Intracellular pH response to hypercapnia in neurons from chemosensitive areas of the medulla.
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髓质化学敏感区域神经元对高碳酸血症的细胞内 pH 反应。
DOI：
10.1152/ajpregu.1997.273.1.r433
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Putnam,RW
中科院分区：
文献类型：
--
作者：
Ritucci,NA;Dean,JB;Putnam,RW
我们研究了延髓的两个化学敏感区[孤束核(NTS)和延髓腹外侧区(VLM)]的神经元对高碳酸血症的反应是否与延髓的两个非化学敏感区[下橄榄核(IO)和舌下核(Hyp)]的神经元不同。取断奶前SD大鼠的延髓脑片，在37℃下用荧光成像系统跟踪单个神经元的细胞内pH(Phi)。在恒定胞外HCO3-浓度[胞外pH(Pho)降低约0.3个pH单位]的情况下，当CO2从5%增加到10%时，NTS和VLM的大部分神经元没有表现出phi恢复(高碳酸酸中毒)。然而，当二氧化碳从5%增加到10%时，在pho不变的情况下，phi恢复。相反，在高碳酸血症期间，IO和Hyp的所有神经元都表现出phi恢复。4，4‘-二异硫氰基二苯乙烯-2，2’-二磺酸不影响4，4‘-二异硫氰基二苯乙烯-2，2’-二磺酸的回收率。这些结果表明：1)延髓化学敏感区(NTS和VLm)和非化学敏感区(IO和Hyp)的Phi调节不同；2)四个区的Phi恢复完全是由于Na+/H+交换；3)NTS和VLM神经元的Na+/H+交换对细胞外酸的抑制比IO和Hyp神经元更敏感。
We investigated whether neurons in two chemosensitive areas of the medulla oblongata [nucleus of the solitary tract (NTS) and ventrolateral medulla (VLM)] respond to hypercapnia differently than neurons in two nonchemosensitive areas of the medulla oblongata [inferior olive (IO) and hypoglossal nucleus (Hyp)]. Medullary brain slices from preweanling Sprague-Dawley rats were loaded with 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein, and intracellular pH (pHi) was followed in individual neurons at 37 degrees C with the use of a fluorescence imaging system. Most neurons from the NTS and VLM did not exhibit pHi recovery when CO2 was increased from 5 to 10% at constant extracellular HCO3- concentration [extracellular pH (pHo) decreased approximately 0.3 pH unit] (hypercapnic acidosis). However, when CO2 was increased from 5 to 10% at constant pHo (isohydric hypercapnia), pHi recovery was seen. In contrast, all neurons from the IO and Hyp exhibited pHi recovery during hypercapnic acidosis. All pHi recovery in the four areas studied was inhibited by 1 mM amiloride and unaffected by 0.5 mM 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid. These data indicate that 1) pHi regulation differs between neurons in chemosensitive (NTS and VLM) and nonchemosensitive (IO and Hyp) areas of the medulla, 2) pHi recovery is due solely to Na+/H+ exchange in all four areas, and 3) Na+/H+ exchange is more sensitive to inhibition by extracellular acidosis in NTS and VLM neurons than in IO and Hyp neurons.