A novel method for measuring membrane conductance changes by a voltage-sensitive optical probe

Yosef Rosemberg, Rafi Korenstein*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


This study presents a method whose principles enable using a voltage-sensitive optical probe, to quantitatively measure conductivity changes elicited in membrane vesicles and cells. The procedure is based on the fact that the amplitude of the transmembrane potential difference, established across a membrane by an external electric field, is decreased when membrane conductivity is increased upon incorporation of ionophores into the membrane. The method was applied to osmotically swollen thylakoid membranes whose membrane conductivity was changed by the addition of gramicidin or ionomycin. The electric field induced stimulated luminescence from photosystem I (electrophotoluminescence-EPL) was used as a voltagesensitive optical probe. We calculated the induced conductance changes by using a calibrated EPL vs external electric field response curve and measuring the ionophore-mediated attenuation of the EPL signal. The calculated ionophore-unmodified conductance of the thylakoid membrane yields a value of 171 ± 56 nS cm. The value of the membrane conductance, modified by 10 nM gramicidin was found to be 190 ± 56 nS cm. The modified membrane conductance and the membrane conductance changes induced by 1 μM ionomycin in the presence of CaCl2 were found to be 186 ± 3 nS cm and 15 ± 3 nS cm, respectively.

Original languageEnglish
Pages (from-to)155-158
Number of pages4
JournalFEBS Letters
Issue number1
StatePublished - 9 Apr 1990


FundersFunder number
USA-Israel BinationalS cienceF oundationt o R.K.


    • Conductance change
    • Electrophotoluminescence
    • Ionophore
    • Photosynthetic membrane
    • Voltage-sensitive optical probe


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