Affordable Access

Photochemical Oxygen Consumption, Oxygen Evolution and Spectral Changes During UVA Irradiation of EMT6 Spheroids¶

American Society for Photobiology
Publication Date
  • Chemistry


Abstract Remarkable rates of oxygen consumption are observed via microelectrode measurements immediately upon the onset of 325 nm irradiation of multicell tumor spheroids. Consumption is irradiance dependent over the range 20–200 mW cm−2, and its magnitude is comparable to that observed previously in the same system using exogenous photosensitizers. Oscillations in the oxygen concentrations suggest that oxygen is also being evolved during irradiation. Oxygen evolution is likely the result of enzymatic dissociation of hydrogen peroxide, which is formed through UV-induced photochemistry. Irradiation of spheroids at 442 and at 514 nm produces a much more modest but detectable oxygen consumption. The dynamics of oxygen concentration changes are quite different at these wavelengths, suggesting a different photochemical mechanism. In these cases, initial oxygen depletion is followed immediately by a more gradual, monotonic increase in the oxygen concentration, consistent with irreversible photobleaching. No oscillations in the oxygen concentration are detectable. At 662 nm, no oxygen consumption was observed over the range of irradiances studied. Fluorescence spectra of cells prior to irradiation include contributions from anthranilic acid and reduced nicotinamide adenine dinucleotide (NADH). During 325 nm irradiation, anthranilic acid is rapidly and irreversibly bleached, while NADH emission undergoes only modest reduction.

There are no comments yet on this publication. Be the first to share your thoughts.


Seen <100 times

More articles like this

Photochemical oxygen consumption, oxygen evolution...

on Photochemistry and Photobiolog... June 2001

A reduction in the in situ rates of oxygen and glu...

on Journal of Cellular Physiology September 1985

Effects of changes in oxygen tension, pH, and gluc...

on International Journal of Radia... Jan 01, 1988

Effects of changes in oxygen tension, pH, and gluc...

on International Journal of Radia... June 1988
More articles like this..