Beeler T, Russell J T, Martonosi A
Eur J Biochem. 1979 Apr;95(3):579-91. doi: 10.1111/j.1432-1033.1979.tb12999.x.
The relationship between Ca2+ fluxes and the ion diffusion potential was analyzed on sarcoplasmic reticulum membranes using oxacarbocyanine dyes as optical probes for membrane potential. 3.3'-Diethyloxodicarbocyanine responds to ATP-induced Ca2+ uptake by isolated sarcoplasmic reticulum vesicles with a decrease in absorbance at 600 nm. The optical change is reversed during Ca2+ release from sarcoplasmic reticulum induced by KCl or by ADP and inorganic phosphate. The absorbance changes are largely attributable to the binding of accumulated Ca2+ to the membrane. There is no indication that sustained changes in membrane diffusion potential would accompany pump-mediated Ca2+ fluxes. A large change in the absorbance of 3,3'-diethyloxodicarbocyanine was observed on sarcoplasmic reticulum vesicles under the influence of membrane potential generated by valinomycin in the presence of a K+ gradient or by ionophore A23187 in the presence of a Ca2+ gradient. The maximum of the potential-dependent absorbance change is at 575--580 nm. The potentials generated by valinomycin or ionophore A23187 are short-lived due to the high permeability of sarcoplasmic reticulum membranes for cations and anions. There is no correlation between the direction and magnitude of the artifically imposed membrane potential and the rate of Ca2+ uptake or release by isolated sarcoplasmic reticulum vesicles.
使用恶嗪碳菁染料作为膜电位的光学探针，分析了肌浆网膜上Ca2+通量与离子扩散电位之间的关系。3,3'-二乙基恶嗪二碳菁对分离的肌浆网小泡中ATP诱导的Ca2+摄取有反应，在600nm处吸光度降低。在KCl或ADP和无机磷酸盐诱导的肌浆网Ca2+释放过程中，光学变化逆转。吸光度变化很大程度上归因于积累的Ca2+与膜的结合。没有迹象表明泵介导的Ca2+通量会伴随膜扩散电位的持续变化。在缬氨霉素存在K+梯度或离子载体A23187存在Ca2+梯度产生的膜电位影响下，在肌浆网小泡上观察到3,3'-二乙基恶嗪二碳菁吸光度的大幅变化。电位依赖性吸光度变化的最大值在575 - 580nm处。由于肌浆网膜对阳离子和阴离子的高渗透性，缬氨霉素或离子载体A23187产生的电位是短暂的。人工施加的膜电位的方向和大小与分离的肌浆网小泡摄取或释放Ca2+的速率之间没有相关性。
