Kariman K, Hempel F G, Jöbsis F F
J Appl Physiol Respir Environ Exerc Physiol. 1983 Oct;55(4):1057-63. doi: 10.1152/jappl.1983.55.4.1057.
We have determined, in vivo and simultaneously, the tissue PO2 (Ptio2) and the oxidation-reduction (redox) state of cytochrome aa3 (cyt aa3) of cat cerebral cortex during and after a short period of N2 breathing. Thirteen cats were anesthetized, ventilated mechanically with room air, subjected to a limited bilateral craniotomy, and then injected with 25 mg/kg of pyrenebutyric acid (PBA) intravenously. Ptio2 was measured from PBA generated fluorescence, emitted by monitored cerebral cortical cells. The cyt aa3 redox state was measured from differential absorption of monochromatic light at 605 vs. 590 nm reflected from the same cortical cells. In response to a 1.5-min N2 ventilation (phase I) the increase in PBA fluorescence signal, indicating a decline in Ptio2, lagged behind the cyt aa3 reduction. When the animal was ventilated with room air (phase II), rapid reoxidation, followed by hyperoxidation of cyt aa3 occurred. The decrease in PBA fluorescence signal, indicating an increase in Ptio2, was seen to lag behind cyt aa3 reoxidation. These results indicate that hysteresis exists in the relation between Ptio2 and cyt aa3 redox state. This may be the result of the situation that 1) low tissue O2 concentration is partially compensated by accumulation of reduced cyt aa3, and 2) following brief periods of anoxia, the affinity of cyt aa3 to O2 is increased.
我们在猫短暂呼吸氮气期间及之后，同时在体内测定了猫大脑皮质的组织氧分压（Ptio2）和细胞色素aa3（cyt aa3）的氧化还原状态。13只猫被麻醉，用室内空气进行机械通气，进行有限的双侧颅骨切开术，然后静脉注射25mg/kg的芘丁酸（PBA）。Ptio2通过监测大脑皮质细胞发出的PBA产生的荧光来测量。细胞色素aa3的氧化还原状态通过测量同一皮质细胞反射的605nm与590nm单色光的吸收差异来测定。在1.5分钟的氮气通气（第一阶段）过程中，PBA荧光信号增加，表明Ptio2下降，但滞后于细胞色素aa3的还原。当动物用室内空气通气时（第二阶段），细胞色素aa3迅速再氧化，随后发生过氧化。PBA荧光信号下降，表明Ptio2增加，滞后于细胞色素aa3的再氧化。这些结果表明，Ptio2与细胞色素aa3氧化还原状态之间的关系存在滞后现象。这可能是由于以下情况导致的：1）低组织氧浓度被还原的细胞色素aa3的积累部分补偿；2）在短暂缺氧后，细胞色素aa3对氧的亲和力增加。
