ACTIVATION OF MITOCHONDRIAL RESPIRATION INDUCED BY LASER IRRADIATION IN THE PRESENCE OF RHODAMINE DYES

The effect of argon laser irradiation (488 and 514 nm) on oxygen consu mption of rat liver mitochondria in the presence of low concentrations of rhodamine dyes (rhodamine 123, ethylrhodamine, and amylrhodamine) was studied. Illumination of rhodamine-sensitized mitochondria stimula tes their respiration; without the rhodamine dye this does not occur. The light-induced uncoupling of respiration was not sensitive to a rad ical scavenger (ionol) or to an inhibitor of the permeability transiti on pore (cyclosporin A). The light-induced respiratory activation corr esponding to mild uncoupling was totally reversible when moderate dose s of irradiation were used. Increasing the irradiation level resulted in only partial restoration of the respiration level in subsequent dar kness. The extent of the light-induced mitochondrial respiratory activ ation was dependent on the rhodamine species.