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Cardiac Output Effects of 03 and No2 Exposure in Healthy Older AdultsNeuroscience Research Institute University of California Santa Barbara, California Eight healthy adults (56-85 yrs) were exposed in an environmental chamber to filtered air (FA), 0.60 ppm NO2, 0.45 ppm 03, and 0.60 ppm NO2 + 0.45 ppm 03 to investigate the effects of NO2 and 03 exposure on cardiac output. The subjects were exposed to each condition for two hours, while they exercised and rested in alternating 20-min periods. Minute ventilation averaged 26-29 l/min among the four exposures. Cardiac output was measured by the noninvasive impedance cardiography method, and was recorded prior to each exposure with the subject at rest, and during the last five minutes of each exercise period. There were no differences in cardiac output at preexposure among the four exposures. The exercise-induced increase in cardiac output with NO2/O 3 exposure was significantly smaller (P < 0.05) than with the FA or 03 alone exposures. Reaction products of inhaled NO 2 are known to cross the lung membranes, probably as a nitrate or nitrite. N02 and 03 are also known to react together to form nitrate and nitrite. We hypothesize that a nitrate or nitrite reaction product of inhaled 03 and NO2 crosses the lung membrane into the general circulation, where it functions as a vasodilator, thereby reducing cardiac output.
Key Words: 2. Key Words: air pollutants • nitrogen dioxide • older adults • oxidants • ozone.
Toxicology and Industrial Health, Vol. 11, No. 1,
99-109 (1995) This article has been cited by other articles:
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