Cardiac Output Effects of 03 and No2 Exposure in Healthy Older Adults

Abstract

Eight healthy adults (56-85 yrs) were exposed in an environmental chamber to filtered air (FA), 0.60 ppm NO2, 0.45 ppm O3, and 0.60 ppm NO2 + 0.45 ppm O3 to investigate the effects of NO2 and O3 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/O3 exposure was significantly smaller (P < 0.05) than with the FA or O3 alone exposures. Reaction products of inhaled NO2 are known to cross the lung membranes, probably as a nitrate or nitrite. NO2 and O3 are also known to react together to form nitrate and nitrite. We hypothesize that a nitrate or nitrite reaction product of inhaled O3 and NO2 crosses the lung membrane into the general circulation, where it functions as a vasodilator, thereby reducing cardiac output.

Cardiovascular effects of ozone in healthy subjects with and without deletion of glutathione-S-transferase M1

“…Drechsler-Parks (Drechsler-Parks, 1995) found that 2-h exposures of 8 healthy subjects to 0.6 ppm NO 2 plus 0.45 ppm ozone, with intermittent exercise, reduced the cardiac output (measured noninvasively by impedance cardiography) relative to air exposure (neither pollutant alone caused a significant effect). This could have been the result of increased pulmonary vascular resistance and reduced left ventricular filling.…”

A cross-disciplinary evaluation of evidence for multipollutant effects on cardiovascular disease

“…There is evidence for greater than additive CVD mortality increases in relation to joint increases in long-term concentrations of O 3 and NO 2 from epidemiologic studies and conflicting evidence between epidemiologic and controlled human exposure studies for a multipollutant effect on CVD-related morbidity of short-term O 3 and NO 2 exposure. An experimental study provides evidence for a synergistic interaction of NO 2 and O 3 combined exposure on reducing cardiac output (Drechsler-Parks, 1995). In epidemiologic studies, no evidence for greater than additive multipollutant effects is indicated for the joint effects of longterm exposure to NO 2 and O 3 on CVD mortality (Jerrett et al, 2013;Crouse et al, 2015).…”

“…We had greater confidence in effect measure modification observed between PM and O 3 in Wong et al (1999) because risk of bias was low or probably low across categories. Several of the experimental studies (Drechsler-Parks, 1995;Farraj et al, 2015;Gliner et al, 1975;Huang et al, 2012;Kodavanti et al, 2011;Kurhanewicz et al, 2014;Tankersley et al, 2013;Wagner et al, 2014) had probably high risk of performance bias (mainly due to insufficient information about blinding to study group), and two of these (Farraj et al, 2015;Kodavanti et al, 2011) also had probably high risk of selection bias (due to insufficient information on randomization of animals and that treatment and data analyses were blinded). These studies with probably high risk of bias had variable results for cardiovascular effects of multipollutant exposure as did the few experimental studies with low or probably low risk of bias across categories (Brook et al, 2009;Fakhri et al, 2009;Urch et al, 2010;Sivagangabalan et al, 2011;Kusha et al, 2012;Wellenius et al, 2004).…”

“…At the same time, experimental studies may minimize uncertainty in exposures present in epidemiologic studies since concentration and duration of the pollutant exposures, composition of the air pollutant mixture, method of delivery, breeding of the animal model, and ambient temperature and filtered air control are usually strictly managed. Several studies (Drechsler-Parks, 1995;Gliner et al, 1975;Kodavanti et al, 2011;Tankersley et al, 2013) involve highly reproducible conditions. However, the studies involving exposure to CAPs collected in different geographic locations are dependent on the composition of the ambient PM on any given day or hour and thus are subject to the same real-life variability in exposure conditions as epidemiologic studies (C. D.…”

Is There Evidence for Synergy Among Air Pollutants in Causing Health Effects?

“…Drechsler-Parks (1995) exposed healthy older adults (five men and one woman, 56–85 years of age, completed the protocol) for 2 hr during intermittent exercise to 450 ppb O 3 , 600 ppb NO 2 , or to O 3 and NO 2 combined. Measurements included respiration, heart rate, cardiac output, and stroke volume.…”