Alteration of mitochondrial membrane potential in photosensitized cardiocytes monitored by fast-response fluorescent probe

Mitochondria constitute well-established target for photodynamic action provided that duration of incubation time with hydrophobic photosensitizer is long enough (18 - 24 hrs) to enable incorporation of the dye into these organelles. It was found that 1 hour incubation of rat cardiocytes with hematoporphyrin dihydrochloride (Hp) followed by low-energy HeNe laser irradiation (ED: 0.3, 1.0, or 3.0 J/cm2), affected mitochondrial membrane potential. The latter was monitored by means of the fast-response fluorescent probe DASPMI and the dynamic video imaging system equipped with frame-grabbing and analyzing software. The time-course of mitochondrial membrane potential decrease exhibited dependence on both: Hp concentration and ED used. In cells incubated with 1 (mu) g/ml Hp a decrease of DASPMI fluorescence occurred during 8 - 15 mins and was preceded by oscillations of fluorescence intensity. For cells incubated with 100 (mu) g/ml Hp disappearance of discrete pattern of mitochondrial fluorescence was observed 1 - 2 mins after irradiation.