The effect of the laser on cellular respiration

Summary A frequency of 5300 Å, derived from a frequency-doubled Q-switched neodymium laser was observed to produce progressive injury and death of cells from a culture of newborn rat cerebellum. A subsequent observation that the green laser frequency (but not 6943 Å of the same intensity from a Q-switched ruby laser) could reduce the rate of oxygen consumption of rat brain cell suspensions suggested that the cytochromes may serve as chromophores. This hypothesis was confirmed by a demonstration that cytochromes c+c₁ failed to act as hydrogen acceptors following 10 impacts of 1 Mw/cm² each of the green laser frequency and cytochromes a+a₃ showed a similar response when a brain cell suspension was irradiated (200 kw) with frequencies of 6096 and 6013 Å. These data illustrate the principle that laser frequencies which are appropriately matched to the absorption characteristics of target molecules can selectively inhibit specific molecular components in intact cells, if a controlled energy density range is used.This work was supported in part by the U.S. Army Medical Research and Development Command, Office of the Surgeon General, under Contract No. DA-49-193-MD-2564, and in part by Electro-Optical Systems, Inc.