ABSTRACT
Following acute occlusion of the proximal left anterior descending (LAD) coronary artery, dogs were exposed continuously for 4 days in an environmental chamber to either 21% or 40% oxygen. Regional transmural myocardial blood flow was then determined by means of radioactive microspheres (8 to 10 microD) while each animal breathed room air (approximately equal to 21% oxygen). Blood flows in the anterolateral and apical regions of the left ventricle in normoxic animals (n = 5) averaged 0.95 +/- 0.03 and 0.69 +/- 0.13 ml/min X gm-1, respectively. In hyperoxic dogs (n = 5), blood flows in these regions were significantly lower, averaging 0.71 +/- 0.07 and 0.28 +/- 0.08 ml/min X gm-1, respectively in the anterolateral free wall, the greatest disparity in perfusion between experimental groups occurred in the subendocardial layers, and macroscopic evidence of necrosis was more widespread after hyperoxia.
Subject(s)
Coronary Disease/chemically induced , Oxygen/administration & dosage , Animals , Arterial Occlusive Diseases/complications , Arterial Occlusive Diseases/physiopathology , Blood Flow Velocity , Body Weight , Chronic Disease , Coronary Circulation , Coronary Disease/complications , Coronary Disease/physiopathology , Dogs , Male , Myocardial Infarction/etiology , Myocardial Infarction/physiopathology , PerfusionABSTRACT
Two experiments were conducted to evaluate the effects of ozone on the electroencephalogram during psychomotor performance. The first experiment consisted of a 2-h visual sustained attention task in room air and 0.75 parts per million (ppm) ozone. The second experiment was a divided attention study which combined a visual choice reaction time situation with an auditory sustained attention task. Ozone levels in this experiment were 0.0 ppm, 0.3 ppm, and 0.75 ppm. Spectral and discriminant function analyses were performed on the EEG collected during these studies. Attempts were made to categorize the EEG between different ozone levels, at rest, during each task performance, and between task and no-task performance within each ambient air condition. Discriminations between conditions for individuals were quite good, but discriminations for the combined subjects were disappointing with the exception of those between task and no-task conditions, which were moderately good.
