A single neuron response to photodynamic effect of various aluminum and zinc phthalocyanines

The photodynamic effects of sulphonated zinc and aluminum phthalocyanine de rivatives as well as phosphonated aluminum phthalOcyanine on the firing of isolated crayfish mechanoreceptor neurons were studied. After 30 min staini ng neurons were irradiated with He-Ne laser (632.8 nm, 0.3 W/cm(2)) and cha nges in neuron firing frequency were recorded. Neuron firing was found to b e very sensitive to photodynamic effect and could serve as a sensitive indi cator of cell photodamage. It changed the firing level and then died at nan omolar concentrations of phthalocyanines. The dynamics of the neuron respon ses to photodynamic effects included stages of firing activation and/or inh ibition prior to irreversible firing abolition. The order of these stages d epended on photosensitizer type and concentration. The comparison of the de pendencies of neuron lifetime on photosensitizer concentrations showed ZnPc S2 to be the most effective photosensitizer. (C) 2000 Elsevier Science Inc. All rights reserved.