Light Dose and Time Dependency of Photodynamic Cell Membrane Damage |
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| Authors: | Takashi Saito Nick A Hartell Hitoshi Muguruma Shu Hotta Satoshi Sasaki Masao Ito Isao Karube |
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| Institution: | Research Center for Advanced Science and Technology, University of Tokyo, Tokyo, Japan;Department of Pharmaceutical and Biological Sciences, Aston University, Birmingham, UK;Department of Environmental Systems Engineering, Kochi University of Technology, Kochi, Japan;Advanced Materials Research Laboratory, Matsushita Research Institute Tokyo, Inc., Kawasaki, Japan;The Institute for Physical and Chemical Research (RIKEN), Wako, Japan |
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| Abstract: | We have investigated the light dose and time dependency of photodynamic cell membrane damage using electrophysiological methods. This study controls the level of cell membrane damage by precisely administration of the light dose. The photosensitizer used was 5′,5″-bis(aminomethyl)-2,2′:5′,2″-terthiophene dihydrochloride (BAT). A confocal laser scanning microscope was used to provide rapid light activation (<1 s) and the subsequent membrane damage was monitored using standard patch clamp techniques. In the presence of 49 μM BAT, light levels less than 0.94 J/cm2 led to a reversible depolarization (20 mV) and reduction of resistance (10%) within 3 s of illumination. Higher intensities of illumination (1.57 J/cm2) caused a complete and irreversible loss of membrane potential and cell membrane resistance within 8 s of illumination. The threshold dose of light required to induce cell death by illumination in the presence of BAT was increased in the presence of the antioxidant Trolox-C. |
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