Kinetics of oxygen consumption after a single flash of light in photoreceptors of the drone (Apis mellifera).
Kinetics of oxygen consumption after a single flash of light in photoreceptors of the drone (Apis mellifera).
复制标题
DOI：
10.1085/jgp.80.1.19
复制
发表时间：
1982-07
期刊：
影响因子：
--
通讯作者：
Poitry S
中科院分区：
文献类型：
--
作者：
Tsacopoulos M;Poitry S
在22摄氏度下，在300微米的雄蜂视网膜切片中测量了单次闪光后氧消耗率（QO 2）的时间过程。为了测量Δ QO 2（t），即QO 2相对于其在黑暗中的水平的变化，用O2微电极同时记录切片中两个部位的O2（PO 2）分压的瞬态，并通过计算机使用傅立叶变换计算Δ QO 2。在40 ms强光闪光后，Δ QO 2达到40微升O2/g.min的峰值，然后以时间常数τ 1 = 4.96 +/- 0.49 s（SD，n = 10）呈指数下降至基线。上升相的特征在于时间常数τ 2 = 1.90 +/- 0.35 s（SD，n = 10）。Δ QO 2的峰值幅度随光强的对数线性增加。用胆碱替代Na+，已知大大降低光诱导的跨膜电流，导致Δ QO 2下降63%。然而，随着这些变化，Δ QO 2（t）的动力学没有变化。这表明，恢复阶段是由一个单一的反应与表观一级动力学的速率限制。提供的证据表明，这种反应可能是钠泵的工作。视网膜暴露于高浓度的哇巴因或毒毛旋花子苷（钠泵抑制剂）降低了约80%的δ QO 2的峰值幅度，并增加了tau蛋白1。tau 1的增加是暴露于心脏活性类固醇的时间的指数函数。因此，似乎Δ QO 2的最大部分用于泵的工作，其活动是Δ QO 2（t）下降分支的速率常数的基础机制。
The time course of the rate of oxygen consumption (QO2) after a single flash of light has been measured in 300-micrometers slices of drone retina at 22 degrees C. To measure delta QO2(t), the change in QO2 from its level in darkness, the transients of the partial pressure of O2 (PO2) were recorded with O2 microelectrodes simultaneously in two sites in the slice and delta QO2 was calculated by a computer using Fourier transforms. After a 40-ms flash of intense light, delta QO2, reached a peak of 40 microliters O2/g.min and then declined exponentially to the baseline with a time constant tau 1 = 4.96 +/- 0.49 s (SD, n = 10). The rising phase was characterized by a time constant tau 2 = 1.90 +/- 0.35 s (SD, n = 10). The peak amplitude of delta QO2 increased linearly with the log of the light intensity. Replacement of Na+ by choline, known to decrease greatly the light-induced transmembrane current, caused a 63% decrease of delta QO2. With these changes, however, the kinetics of delta QO2 (t) were unchanged. This suggest that the recovery phase is rate-limited by a single reaction with apparent first-order kinetics. Evidence is provided that suggests that this reaction may be the working of the sodium pump. Exposure of the retina to high concentrations of ouabain or strophanthidin (inhibitors of the sodium pump) reduced the peak amplitude of delta QO2 by approximately 80% and increased tau 1. The increase of tau 1 was an exponential function of the time of exposure to the cardioactive steroids. Hence, it seems likely that the greatest part of delta QO2 is used for the working of the pump, whose activity is the mechanism underlying the rate constant of the descending limb of delta QO2 (t).