Photodynamic effect of deuteroporphyrin IX and hematoporphyrin derivativeson single neuron

The photodynamic effects of 6 new deuteroporphyrin IX derivatives with diff erent amphiphilicity and lipophilicity, as well as effects of known hematop orphyrin derivatives Photofrin II and Photoheme on isolated crayfish mechan oreceptor neurons were studied. After 30 min photosensitization, neurons we re irradiated with He-Ne laser (632.8 nm, 0.3 W/cm(2)), and changes in thei r firing frequency were recorded, Neuron firing was shown to be very sensit ive to photodynamic effect of the studied deuteroporphyrin M derivatives ca using irreversible firing abolition at pikomolar concentrations while Photo heme and Photofrin II were effective in the nanomolar range. The most effec tive sensitizers were 4-(1-methyl-3-hydroxybutyl) and 4-(1-methyl-2-acetyl- 3 oxobutyl)-deuteroporphyrins. Extinction and amphiphilicity were shown to be the most important properties determining photodynamic efficiency of the studied photosensitizers. (C) 2001 Academic Press.