Light and electron microscopic examinations of experimentally produced heart muscle necroses following normobaric hyperoxia.

Heart muscle necroses following normobaric hyperoxia as examined under a light microscope occur after 40 hours exposure in the rabbit and increase in intensity with prolongation of the exposition time. Simultaneous arterial blood gas analysis excludes a hypoxemis as the cause, In addition electron microscopic examination of the necroses demonstrate the primary changes in the myofibrils but not in the mitochondria. The ultramorphological picture is however, quite similar to the myocardial necroses after epinephrine application in the rabbit. A pathogenetic relationship between heart muscle necroses after normobaric hyperoxia and after epinephrine should be considered.