Cell attachment to extracellular matrices is modulated by pulsed radiation at 820 nm and chemicals that modify the activity of enzymes in the plasma membrane.

BACKGROUND AND OBJECTIVES: Adhesive interactions between cells and extracellular matrices play a regulative role in wound repair processes. The objective of this investigation is to study action mechanisms of pulsed radiation at 820 nm on cellular adhesion in vitro. Light emitting diodes (LED) at 820 nm are widely used for treatment of wounds of various etiology. STUDY DESIGN/MATERIALS AND METHODS: The LED (820 +/- 10 nm, 10 Hz, 16-120 J/m(2)) is used for the irradiation of HeLa cell suspension. In parallel experiments, amiloride (5 x 10(-4) M), ouabain (7 x 10(-5) M, 7 x 10(-4) M), quinacrine (6 x 10(-4) M), arachidonic acid (1 x 10(-5) M), glucose (2 x 10(-4) M), and ATP (5 x 10(-5) M) are added to the cell suspension before or after the irradiation procedure. The cell-glass adhesion is studied using the adhesion assay technique described in Lasers Surg Med 1996; 18:171. RESULTS: Cell-glass adhesion increases in a dose-dependent manner following the irradiation. Preirradiation eliminates the inhibition of cell attachment caused by ouabain, arachidonic acid, and ATP. The inhibitive effect of quinacrine on the cell attachment is eliminated by the irradiation performed after the treatment with the chemical. Irradiation and amiloride have a synergetic stimulative effect on the cell attachment. The threshold dose for the cell attachment stimulation by the irradiation is decreased by the treatment of the cell suspension with amiloride or ouabain. CONCLUSIONS: The results obtained indicate that pulsed IR radiation at 820 nm increases the cell-matrix attachment. It is the modulation of the monovalent ion fluxes through the plasma membrane and not the release of arachidonic acid that is involved in the cellular signaling pathways activated by irradiation at 820 nm. Preirradiation has a protective effect against the inhibitive action of ouabain, arachidonic acid, ATP, and quinacrine on cell attachment process. It is supposed that irradiation activates those signaling pathways in cells which attenuate the inhibitive action of these chemicals.

Photostability studies of ouabain, alpha-acetyldigoxin and digoxin in solid state.

Ouabain, alpha-acetyldigoxin and digoxin were subjected to irradiation using different light sources in crystalline state and their respective yields of photoproducts were determined densitometrically. alpha-Acetyldigoxin was found to be less stable than digoxin yielding a higher percentage of photoproducts under each light source examined. Ouabain showed photostability under the conditions of investigation.

Duality of alpha-subunit of canine kidney sodium- and potassium-activated adenosinetriphophatase in electrophoresis.

Sodium- and potassium-activated adenosinetriphosphatase (Na+, K+-ATPase) purified from dog kidney outer medulla was examined by polyacrylamide gel electrophoresis and by photoaffinity labeling with N-(ouabain)-N'-(2-nitro-4-azidophenyl)-ethylenediamine (NAP-ouabain). The large subunit band (alpha-band) split into two bands on the gel after the enzyme was heat-treated in the presence of 1% sodium dodecylsulfate (SDS). Of the two bands (alpha I and alpha II), alpha I had the same electrophoretic mobility as the original band, while alpha II moved slightly faster. Total conversion into alpha II was not observed, about half of the original remaining as alpha I. Below 60 degree C, heat treatment did not produce alpha II. Phenylmethylsulfonyl fluoride did not prevent the appearance of alpha II. Both alpha I and alpha II were labeled with [3H]NAP-ouabain. Nonspecific incorporation of [3H]NAP-ouabain also occurred irrespective of illumination, but it was removed either by diffusion during staining and destaining of the gel or by treatment of the enzyme with trichloroacetic acid. It is tentatively concluded that the splitting of the band reflects some intrinsic differences in situ of the alpha-subunit of dog kidney membrane Na+,K+-ATPase.