Effect of Red Laser Light on Na +,K + -ATPase Activity in Human Erythrocyte Membranes Sensitized with Zn-Phthalocyanine

Abstract

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 μmol 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 μM) stimulated enzyme activity. The concentration of 2 μM 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 μM) 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.