Younkin D P, Wagerle L C, Chance B, Maria J, Delivoria-Papadopoulos M
J Appl Physiol (1985). 1987 Apr;62(4):1569-74. doi: 10.1152/jappl.1987.62.4.1569.
We measured cerebral phosphocreatine (PCr), inorganic phosphate (Pi), ATP, and intracellular pH (pHi) with in vivo phosphorus nuclear magnetic resonance (NMR) during 10- to 15-min periods of reversible hypoxic hypoxia in 20 newborn lambs (1-11 days). There was a significant correlation between arterial O2 partial pressure (PaO2) and the PCr/Pi ratio or pHi; however, between PaO2 130-33 mmHg, metabolite changes were not significant. PCr/Pi and pHi decreased significantly when PaO2 was lowered below 33 and 28 mmHg, respectively. After recovery, metabolite ratios and pHi returned to base-line values within 5 min. During the early phases of hypoxia and recovery, there were large fluctuations in metabolites and pHi, indicating that mitochondrial reactions were not in a steady state. After several minutes of hypoxia or recovery, PCr/Pi and pHi stabilized, suggesting steady state kinetics for mitochondrial respiration. NMR is extremely sensitive to changes in mitochondrial oxygenation, and stable PCr/Pi and pHi indicate that O2 tension in cerebral mitochondria of the newborn lamb is constant between PaO2 of 30 and 140 mmHg.
我们在20只新生羔羊（1至11日龄）可逆性低氧缺氧10至15分钟期间，采用活体磷核磁共振（NMR）测量了脑磷酸肌酸（PCr）、无机磷酸盐（Pi）、三磷酸腺苷（ATP）和细胞内pH值（pHi）。动脉血氧分压（PaO2）与PCr/Pi比值或pHi之间存在显著相关性；然而，在PaO2为130至33 mmHg之间时，代谢物变化并不显著。当PaO2分别降至33 mmHg和28 mmHg以下时，PCr/Pi和pHi显著降低。恢复后，代谢物比值和pHi在5分钟内恢复至基线值。在缺氧和恢复的早期阶段，代谢物和pHi有较大波动，表明线粒体反应并非处于稳定状态。缺氧或恢复几分钟后，PCr/Pi和pHi趋于稳定，提示线粒体呼吸的稳态动力学。NMR对线粒体氧合变化极为敏感，稳定的PCr/Pi和pHi表明新生羔羊脑线粒体中的氧张力在PaO2为30至140 mmHg之间保持恒定。
