Biochemical and histological effects of intermittent carbon monoxide exposure in cynomolgus monkeys (Macaca fascicularis) in relation to atherosclerosis.

The data in this report do not suggest any association between periodic carbon monoxide exposure and the development of atherosclerosis in cynomolgus monkeys. Animals were exposed to 200 to 400 ppm CO in the inspired air for 10 alternate half hours daily for approximately 12 months. These conclusions are reached from both histological and biochemical studies (aortic cholesterol content, arterial cholesterol influx, aortic oxygen consumption, as well as plasma triglyceride concentrations and HDL cholesterol to total cholesterol ratios). A rise in plasma and tissue free fatty acids (FFA) was observed in the experimental group exposed to carbon monoxide. However, the increase in FFA tissue levels was not believed to be due to any inhibitory effect of CO on the electron transfer system since mitochondrial respiratory function was not depressed.