Primary fluorescence of rat muscle after CO2 laser thermal injury.

Observations are reported indicating that CO2 laser radiation induces the appearance of strong primary fluorescence in the tissues surrounding the incidence zone of the beam. The characteristics of this emission were studied by means of cytofluorometric techniques on rat muscles and compared with the fluorescence obtained by a heating procedure or by storage of tissue slices. Laser-induced primary fluorescence was found to be related to the thermal effect of CO2 laser radiation. Moreover, evidence is provided that the processes occurring during heating and those occurring during tissue decomposition most probably produce the same fluorescent products, albeit with different rates. From the results obtained, it is suggested that primary fluorescence can be used as a marker of the damage suffered by the irradiated tissues.