Effect of red laser light on Na+,K+-ATPase activity in human erythrocyte membranes sensitized with Zn-phthalocyanine

Objective: The influence of laser light (670 nm) on human erythrocyte membrane Na+,K+-ATPase activity in the presence and absence of Zn-phthalocyanine (ZnPc) was studied. Background Data: The response of erythrocyte membranes to low-power laser irradiation has not been fully elucidated. In our study, we focused on the studies on photo-induced changes of Na+,K+-ATPase activity. The erythrocyte membrane suspensions were incubated with 2 mM of ZnPc and next irradiated with energy doses of 19.1, 38.2, 57.3, 76.4, and 95.5 J.cm(-2). Materials and Methods: The activity of Na+,K+-ATPase was assayed colorimetrically at the wavelength of 820 nm and expressed in mumol of inorganic phosphate released from ATP per mg of protein. Results: The measurements of Na+,K+-ATPase activity in erythrocyte membranes incubated with ZnPc in the dark demonstrated that all concentrations of the dye (0.5, 1, 2, and 3 muM) stimulated enzyme activity. The concentration of 2 muM caused the smallest increase of enzyme activity, so this concentration was accepted for further studies. Irradiation of erythrocyte membranes in the presence of the dye (2 muM) significantly decreased Na+,K+-ATPase activity. Only for energy doses of 19.1 and 38.2 J.CM-2 was the enzyme activity comparable to the activity of the control. Conclusion: It was found that irradiation with all energy doses applied caused a rise of enzyme activity. In the presence of ZnPc, significant decrease of Na+,K+-ATPase activity was observed.