Assessment of membrane potential changes using the carbocyanine dye,diS-C3-(5): synchronous excitation spectroscopy studies
✍ Scribed by J. Plášek; V. Hrouda
- Publisher
- Springer
- Year
- 1991
- Tongue
- English
- Weight
- 587 KB
- Volume
- 19
- Category
- Article
- ISSN
- 1432-1017
No coin nor oath required. For personal study only.
✦ Synopsis
The fluorescence of the voltage sensitive dye, diS-C3-(5 ), has been analyzed by means of synchronous excitation spectroscopy. Using this rather rare fluorescence technique we have been able to distinguish between the slightly shifted spectra of diS-C3-(5)fluorescence from cells and from the supernatant. It has been found that diS-C3-(5) fluorescence in the supernatant can be selectively monitored at 2exo = 630 nm and 2~m = 650 nm, while the cell associated fluorescence can be observed at 2ex o = 690 nm and 2ore = 710 rim. A modified theory for the diS-C3-(5) fluorescence response to the membrane potential is presented, according to which a linear relationship exists between the logarithmic increment of the dye fluorescence intensity in the supernatant, In I/I °, and the underlying change in the plasma membrane potential, A~,v=~v-~b~. The theory has been tested on human myeloid leukemia cells (line ML-1) in which membrane potential changes were induced by valinomycin clamping in various K ÷ gradients. It has been demonstrated that the membrane potential change, A0,, can be measured on an absolute scale.