Evidence for second metabolic pathway for O2 from PtiO2 measurements in denervated cat carotid body.
Evidence for second metabolic pathway for O2 from PtiO2 measurements in denervated cat carotid body.
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来自去神经猫颈动脉体中 PtiO2 测量的 O2 第二种代谢途径的证据。
DOI：
10.1152/jappl.1989.67.4.1578
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Whalen,WJ
中科院分区：
文献类型：
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作者：
Buerk,DG;Nair,PK;Whalen,WJ
在猫颈动脉体（CB）中进行了O2微电极研究，以探讨除了经典的氧化代谢外，O2还存在第二种低亲和力代谢途径的假设。用凹式阴极微电极（尖端直径小于5 μ m）测量15只正常猫（对照组）150个部位和5只实验前2或3天失神经支配的猫154个部位短暂血流阻断后的组织PO 2（PtiO 2）和O2消失率（dPO 2/dt）。去神经支配CB的平均PtiO 2略高：79.6 +/- 1.6（SE）Torr，而对照组为76.4 +/- 2.0 Torr（P =不显著）。平均dPO 2/dt快8.4%：-8.42 +/- 0.28 Torr/s，对照组为-7.77 +/- 0.43 Torr/s（P <0.05）。根据猫氧合血红蛋白校正的dPO 2/dt计算的耗氧率（VO 2）高7.5%：失神经和对照CBs分别为1.62和1.51 ml.100 g-1.min-1（P <0.05）。测定每个O2消失曲线的表观Michaelis-Menten常数Kmapp（定义为PtiO 2，其中dPO 2/dt在闭塞后的前3 s内从初始速率下降50%）。去神经支配后，Kmapp显著降低-47%：12.0 +/-1.3托，而对照组为22.6 +/-2.5托（P <0.01）。这些数据为CB中O2的第二代谢途径提供了证据，该途径在去神经支配后失去了对VO 2的影响。
O2 microelectrode studies were conducted in the cat carotid body (CB) to investigate the hypothesis that there is a second, low affinity metabolic pathway for O2 in addition to classical oxidative metabolism. Tissue PO2 (PtiO2) and O2 disappearance rates (dPO2/dt) after brief blood flow occlusion were measured with recessed cathode microelectrodes (tip diameter less than 5 microns) at 150 sites in 15 normal cats (controls) and at 154 sites in 5 cats in which one CB had been denervated 2 or 3 days before the experiments. Mean PtiO2 was slightly higher in denervated CBs: 79.6 +/- 1.6 (SE) Torr compared with 76.4 +/- 2.0 Torr for controls (P = not significant). Mean dPO2/dt was 8.4% faster: -8.42 +/- 0.28 Torr/s compared with -7.77 +/- 0.43 Torr/s for controls (P less than 0.05). The O2 consumption rate (VO2), calculated from dPO2/dt correcting for cat oxyhemoglobin, was 7.5% higher: 1.62 and 1.51 ml.100 g-1.min-1, respectively, for denervated and control CBs (P less than 0.05). The apparent Michaelis-Menten constant, Kmapp (defined as the PtiO2 where dPO2/dt decreased by 50% from the initial rate during the first 3 s after occlusion) was determined for each O2 disappearance curve. After denervation, Kmapp decreased significantly by -47%: 12.0 +/- 1.3 Torr compared with 22.6 +/- 2.5 Torr for controls (P less than 0.01). The data provide evidence for a second metabolic pathway for O2 in the CB that loses its influence on VO2 after denervation.