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Effect of Membrane Potential on the Binding of Merocyanine 540 to Human Erythrocytes
Author(s) -
Lagerberg Johan W. M.,
VanSteveninck John,
Dubbelman Tom M. A. R.
Publication year - 1998
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1998.tb09117.x
Subject(s) - hyperpolarization (physics) , depolarization , chemistry , membrane , biophysics , membrane potential , photosensitizer , binding site , in vitro , biochemistry , photochemistry , biology , stereochemistry , nuclear magnetic resonance spectroscopy
Illumination of erythrocytes in the presence of merocyanine 540 (MC540) resulted in changed binding characteristics of MC540, i.e. a red shift in the emission maximum of bound dye with an increase in the relative fluorescence quantum yield. Aluminum phthalocyanine tetrasulfonate‐mediated photodynamic treatment, before addition of MC540, resulted in a comparable change in the MC540‐binding characteristics with, in addition, an increase in the concentration of MC540 in the membrane. Both photodynamic treatments induce depolarization of the red cell membrane, with a dose dependency comparable to that of changed MC540 binding. Also depolarization, induced by incubation of the cells with A23187 in the presence of Ca 2 + in high [K+] buffer, resulted in similar changes in the MC540 binding characteristics. These results indicate a relation between photodynamically induced membrane depolarization and changed MC540‐binding characteristics. Hyperpolarization induced by incubation with A23187 in low [K+] buffer resulted in decreased binding of MC540. In accordance, the MC540‐mediated photodamage to red cells decreased upon hyperpolarization of the cells. The results indicate that the binding of MC540 to erythrocytes is strongly dependent on the membrane potential and that hyperpolarization of the membrane could be a possible protection mechanism for erythrocytes against MC540‐mediated photodynamic damage.