Abstract

Laser irradiated mitochondria in rat myocardial cells were analysed cytochemically for succinic dehydrogenase and with the electron microscope for ultrastructure. The least severe lesion type did not alter the SDH activity of the mitochondria. The major ultrastructural alteration observed was an electron-dense region corresponding to a phase-dark spot in the light micrographs. This lesion appeared to be restricted in depth and width within the irradiated structure. The damage was primarily localized to the intercristae matrix. The cristae appeared normal. © 1973.