Carbon Monoxide

Dr. Thom and Dr. Ischiropoulos at the University of Pennsylvania Medical Center examined the effects of low concentrations of carbon monoxide on platelets and cells isolated from blood vessels. The investigators exposed blood platelets (taken from rats) and endothelial cells (isolated from bovine blood vessels) to varying concentrations of carbon monoxide and measured how much nitric oxide was released. To determine if exposure to carbon monoxide causes endothelial cells to produce peroxynitrite, the investigators looked for markers of its presence in the culture medium and in the cells.

Carbon monoxide is a ubiquitous air pollutant. It is found in cigarette smoke and emissions from motor vehicles, industrial processes, and poorly ventilated combustion sources. Dr. Penn and his colleagues at New York University Medical Center sought to determine whether chronic exposure to ambient levels of carbon monoxide is also a risk factor for developing atherosclerosis because this disease is the leading contributor to deaths by heart attack and stroke in the United States.

Dr. Sheps and colleagues assessed the effect of exposure to carbon monoxide (CO) on ventricular arrhythmias in 41 nonsmoking human volunteers with coronary artery disease. On 3 consecutive days, volunteers were exposed in random order to air, 100 ppm CO (target 4% carboxyhemoglobin), and 200 ppm CO (target 6% carboxyhemoglobin), followed by a bicycle exercise test. Radionuclide cardiac ventriculography and ambulatory electrocardiogram were performed at rest and during exercise.

This report describes a study by Dr. Verrier and colleagues to explore the effects of acute carbon monoxide (CO) exposure on cardiac electrical stability through a number of biological models. Experiments involved cardiac electrical testing of conscious and anesthetized dogs with normal and ischemic hearts who were exposed to CO for 2 or 24 hours. The experimental plan explored both the direct effects of CO exposure on the myocardium and possible indirect effects through alterations in the ability of platelets to aggregate or changes in nervous system activity.