Effects of photodynamic action on energy coupling of Ca2+ uptake in liver mitochondria.
In mitochondria isolated from rat liver, incubated in the presence of 6 X 10(-3) mM hematoporphyrin and irradiated with UV light at 365 nm, respiration, oxidative phosphorylation and Ca2+ uptake were measured in order to determine the respective photosensitivity of these functions. Irradiation with increasing doses produces uncoupling of oxidative phosphorylation followed by inhibition of Ca2+ uptake and finally arrest of respiration. Ca2+ uptake stimulated by the addition of ATP was also studied in mitochondria uncoupled by irradiation which were still able to concentrate Ca2+ aerobically. Anaerobic Ca2+ uptake driven by ATP hydrolysis was found to be similar in control and in irradiated mitochondria, suggesting a different photosensitivity for the ATPase as compared to the ATP-synthase activity.
D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism*; D007700:Kinetics; D008930:Mitochondria, Liver / Q000378:metabolism* / Q000528:radiation effects; D010101:Oxygen Consumption / Q000528:radiation effects*; D051381:Rats; D011919:Rats, Inbred Strains; D014466:Ultraviolet Rays
D002118:Calcium