Biostimulation of Na,K-ATPase by low-energy laser irradiation (685 nm, 35 mW):: Comparative effects in membrane, solubilized and DPPC:DPPE-liposome reconstituted enzyme

Objective: The aim of the present work was to investigate the effect of low-energy laser irradiation (685 run, 35 mW) on the ATPase activity of the different forms of the Na,K-ATPase. Methods: Membrane-bound and solubilized (alpha beta)(2) form of Na,K-ATPase was obtained from the dark red outer medulla of the kidney and proteoliposomes of DPPC:DPPE and Na,K-ATPase was prepared by the co-solubilization method. Irradiations were carried out at 685 nm using an InGaAIP diode laser. Results: The ATPase activity of the membrane fraction was not altered with exposition to irradiation doses between 4 and 24 J/cm(2). However, with irradiation doses ranging from 32 to 40 J/cm(2), a 28% increase on the ATPase activity was observed while when using up to 50 J/cm(2) no additional enhancement was observed. When biostimulation was done using the solubilized and purified enzyme or the DPPC:DPPE-liposome reconstituted enzyme, an increase of about 36-40% on the ATPase activity was observed using only 48 J/cm(2). With irradiation above these values (24 J/cm(2)) no additional increase in the activity was observed. These studies revealed that the biostimulation of ATPase activity from different forms of the Na,K-ATPase is dose dependent in different ranges of irradiation exposure. The stimulation promoted by visible laser doses was modulated and the process was reverted after 2 It for the enzyme present in the membrane and after about 5 h for the solubilized or the reconstituted in DPPC:DPPE-liposomes. (c) 2007 Elsevier B.V. All rights reserved.