Ozone-induced hypothermia and bradycardia in rats and guinea pigs in nose-only or whole-body inhalation systems

Campen, Matthew J.; Norwood, Joel; McKee, J.; Mebane, Rudolph; Hatch, Gary E.; Watkinson, William P.

doi:10.1016/s0306-4565(99)00041-8

Cited by 6 publications

(2 citation statements)

References 15 publications

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“…This hypothermic response has been shown to be much greater in mice (5), where exposure to 2.0 ppm O 3 produced decreases in HR of 200-250 bpm and decreases in T co of 9-10°C ( Figure 2). Interestingly, guinea pigs do not appear to demonstrate a hypothermic response following exposure to up to 2.0 ppm O 3 (23). Despite consistent, significant decreases in the above-described parameters, there was essentially no lethality in any of the studies conducted at standard room temperature.…”

Section: Ozone Inhalationmentioning

confidence: 82%

Cardiovascular and Systemic Responses to Inhaled Pollutants in Rodents: Effects of Ozone and Particulate Matter

Watkinson¹,

Campen²,

Nolan³

et al. 2001

Environmental Health Perspectives

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539Over the past decade our laboratory has been investigating the nature and extent of specific extrapulmonary responses observed in rodents following exposure to ambient pollutants and other xenobiotic agents. These responses are characterized by primary decreases in important indices of cardiac and thermoregulatory functions, along with secondary decreases in associated parameters. The summation of these effects, termed the hypothermic response (1), has both physiological and behavioral components, appears to be most pronounced in (and possibly unique to) the rodent, and may significantly impact the interpretation of experimental data and its subsequent extrapolation to the human situation. Typically, healthy adult rats may exhibit decreases in heart rate (HR) of 50-100 beats per minute (bpm) and decreases in core temperature (T co ) of 1.5-2.5°C following routine exposures to moderate levels of ambient pollutants, such as ozone (O 3 ) or particulate matter (PM). In addition, there appear to be similar, albeit related, decreases in other functional parameters, including metabolism, minute ventilation, blood pressure, and cardiac output. Furthermore, it has been demonstrated that the magnitudes of these observed decreases may be significantly modulated by changes in experimental conditions. For example, experimental stresses related to exercise, restraint, and handling, as well as the imposition of changes in ambient temperature (T a ), have all been shown to have profound effects on these responses. Finally, it has been proposed that a moderate hypothermic response may afford protection and improve survivability following toxic exposures, whereas a more severe response may actually potentiate the toxicity. Although the underlying mechanisms of the hypothermic response are still largely unexplored and unknown, preliminary experimental evidence suggests that these effects may be mediated, at least partly, via components of the parasympathetic nervous system. O 3 is a ubiquitous ambient pollutant and a known pulmonary irritant (2). In a series of earlier studies from our laboratory (3-6), we investigated both the pulmonary and systemic consequences of O 3 exposures (0.25-2.0 ppm) in rodents. With respect to nonpulmonary end points, these studies used radiotelemetry procedures to examine HR, T co , and electrocardiographic changes in rats and mice over a variety of experimental conditions. These studies were among the first to report consistent, robust concentration-related decreases in the abovementioned parameters in rodents following exposure to routine experimental levels of O 3 .More recently, the putative toxicity of PM has attracted considerable attention, and numerous epidemiological studies published over the last few years have reported a slight but consistent association between the concentration of ambient PM and the incidence of adverse health effects in man (7-12). Despite limited supporting experimental evidence, there is a growing consensus that higher levels of PM in the air are associated with in...

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Section: Ozone Inhalationmentioning

confidence: 82%

Cardiovascular and Systemic Responses to Inhaled Pollutants in Rodents: Effects of Ozone and Particulate Matter

Watkinson¹,

Campen²,

Nolan³

et al. 2001

Environmental Health Perspectives

Self Cite

View full text Add to dashboard Cite

show abstract

Section: Ozone Inhalationmentioning

confidence: 82%

Cardiovascular and systemic responses to inhaled pollutants in rodents: effects of ozone and particulate matter.

Watkinson

Campen

Nolan

et al. 2001

Environ Health Perspect

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Striking similarities have been observed in a number of extrapulmonary responses of rodents to seemingly disparate ambient pollutants. These responses are often characterized by primary decreases in important indices of cardiac and thermoregulatory function, along with secondary decreases in associated parameters. For example, when rats are exposed to typical experimental concentrations of ozone (O(3), they demonstrate robust and consistent decreases in heart rate (HR) ranging from 50 to 100 beats per minute, whereas core temperature (T(co) often falls 1.5-2.5 degrees C. Other related indices, such as metabolism, minute ventilation, blood pressure, and cardiac output, appear to exhibit similar deficits. The magnitudes of the observed decreases may be modulated by changes in experimental conditions and appear to vary inversely with both ambient temperature and body mass. More recent studies in which both healthy and compromised rats were exposed to either particulate matter or its specific components yielded similar results. The agents studied included representative examples of ambient, combustion, and natural source particles, along with individual or combined exposures to their primary metallic constituents. In addition to the substantial decreases in HR and T(co), similar to those seen with the O(3)-exposed rats, these animals also displayed numerous adverse changes in electrocardiographic waveforms and cardiac rhythm, frequently resulting in fatal outcomes. Although there is only limited experimental evidence that addresses the underlying mechanisms of these responses, there is some indication that they may be related to stimulation of pulmonary irritant receptors and that they may be at least partially mediated via the parasympathetic nervous system.

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Effects of Ozone on Evaporative Water Loss and Thermoregulatory Behavior of Marine Toads (Bufo marinus)

Dohm

Mautz

Looby

et al. 2001

Environmental Research

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Ozone-induced hypothermia and bradycardia in rats and guinea pigs in nose-only or whole-body inhalation systems

Cited by 6 publications

References 15 publications

Cardiovascular and Systemic Responses to Inhaled Pollutants in Rodents: Effects of Ozone and Particulate Matter

Cardiovascular and Systemic Responses to Inhaled Pollutants in Rodents: Effects of Ozone and Particulate Matter

Cardiovascular and systemic responses to inhaled pollutants in rodents: effects of ozone and particulate matter.

Effects of Ozone on Evaporative Water Loss and Thermoregulatory Behavior of Marine Toads (Bufo marinus)

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