Breathing pattern and metabolic rate responses of rats exposed to ozone

Mautz, William J.; Bufalino, Charles

doi:10.1016/0034-5687(89)90018-2

Cited by 41 publications

(30 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The mechanism of action of this effect is not well understood. In view of the reduction in HR occurring concomitantly with the hypothermia, it is likely that rats exposed to O 3 sustain reductions in metabolic heat production (Mautz & Bufalino, 1989). However, the episodic exposure paradigm of the current study revealed an exacerbation of the hypothermic and bradycardic effects of O 3 on the second consecutive day of exposure.…”

Section: Discussioncontrasting

confidence: 57%

“…Mautz & Bufalino (1989) showed that the hypothermic response to 0.8 ppm O 3 in rats was protective. When exposed to this concentration of O 3 in a plethysmograph, breathing pattern became shallow and more rapid, resulting in a significant drop in minute ventilation and a $25% drop in metabolic rate as core temperature decreased by $1.4 C. The authors concluded that an air pollutantinduced reduction in body temperature, and consequently, metabolism and ventilation, can be viewed as a mechanism of pulmonary defense available to rodents that can quickly lower their core temperature (for discussion, see Gordon, 2005).…”

Section: Discussionmentioning

confidence: 98%

See 1 more Smart Citation

Episodic ozone exposure in adult and senescent Brown Norway rats: acute and delayed effect on heart rate, core temperature and motor activity

Gordon

Johnstone

Aydin

et al. 2014

Inhalation Toxicology

View full text Add to dashboard Cite

Setting exposure standards for environmental pollutants may consider the aged as a susceptible population but the few published studies assessing susceptibility of the aged to air pollutants are inconsistent. Episodic ozone (O₃) is more reflective of potential exposures occurring in human populations and could be more harmful to the aged. This study used radiotelemetry to monitor heart rate (HR), core temperature (T(c)) and motor activity (MA) in adult (9-12 months) and senescent (20-24 months) male, Brown Norway rats exposed to episodic O₃ (6 h/day of 1 ppm O₃ for 2 consecutive days/week for 13 weeks). Acute O₃ initially led to marked drops in HR and T(c). As exposures progressed each week, there was diminution in the hypothermic and bradycardic effects of O₃. Senescent rats were less affected than adults. Acute responses were exacerbated on the second day of O₃ exposure with adults exhibiting greater sensitivity. During recovery following 2 d of O₃, adult and senescent rats exhibited an elevated T(c) and HR during the day but not at night, an effect that persisted for at least 48 h after O₃ exposure. MA was elevated in adults but not senescent rats during recovery from O₃. Overall, acute effects of O₃, including reductions in HR and T(c), were attenuated in senescent rats. Autonomic responses during recovery, included an elevation in T(c) with a pattern akin to that of a fever and rise in HR that were independent of age. An attenuated inflammatory response to O₃ in senescent rats may explain the relatively heightened physiological response to O₃ in younger rats.

show abstract

Section: Discussioncontrasting

confidence: 57%

Section: Discussionmentioning

confidence: 98%

Episodic ozone exposure in adult and senescent Brown Norway rats: acute and delayed effect on heart rate, core temperature and motor activity

Gordon

Johnstone

Aydin

et al. 2014

Inhalation Toxicology

View full text Add to dashboard Cite

show abstract

“…V O 2 and V CO 2 in normoxia were at their lowest, but V E/V O 2 and V E/V CO 2 ratios were at their highest at P0 -P1 compared with the rest of the first 3 postnatal weeks. Greater or lesser V E/V O 2 and V E/V CO 2 ratios than normal generally imply hyperventilation or hypoventilation, respectively (19,37,52) and may indicate ventilatory perturbations (14,48). Thus the normal state at P0 -P1 is a combination of a relatively high rate of ventilation and a relatively low rate of metabolism, the exact opposite to that during the rest of the first week.…”

Section: Discussionmentioning

confidence: 99%

Postnatal development of metabolic rate during normoxia and acute hypoxia in rats: implication for a sensitive period

Liu¹,

Fehring²,

Lowry³

et al. 2009

Journal of Applied Physiology

View full text Add to dashboard Cite

Liu Q, Fehring C, Lowry TF, Wong-Riley MTT. Postnatal development of metabolic rate during normoxia and acute hypoxia in rats: implication for a sensitive period. J Appl Physiol 106: 1212-1222, 2009. First published December 31, 2008 doi:10.1152/japplphysiol.90949.2008.-Previously, we reported that the hypoxic ventilatory response (HVR) in rats was weakest at postnatal day (P) P13, concomitant with neurochemical changes in respiratory nuclei. A major determinant of minute ventilation (V E) is reportedly the metabolic rate [O2 consumption (V O2) and CO2 production (V CO2)]. The present study aimed at testing our hypothesis that daily metabolic rates changed in parallel with ventilation during development and that a weak HVR at P13 was attributable mainly to an inadequate metabolic rate in hypoxia. Ventilation and metabolic rates were monitored daily in P0 -P21 rats. We found that 1) ventilation and metabolic rates were not always correlated, and V E/V O2 and V E/V CO2 ratios were not constant during development; 2) metabolic rate and V E/V O2 and V E/V CO2 ratios at P0 -P1 were significantly different from the remaining first postnatal week in normoxia and hypoxia; 3) at P13, metabolic rates and V E/V O2 and V E/V CO2 ratios abruptly increased in normoxia and were compromised in acute hypoxia, unlike more stable trends during the remaining second and third postnatal weeks; and 4) the respiratory quotient (V CO2/V O2) was quite stable in normoxia and fluctuated slightly in hypoxia from P0 to P21. Thus our data revealed heretofore unsuspected metabolic adjustments at P0 -P1 and P13. At P0 -P1, ventilation and metabolic rates were uncorrelated, whereas at P13, they were closely correlated under normoxia and hypoxia. The findings further strengthened the existence of a critical period of respiratory development around P13, when multiple physiological and neurochemical adjustments occur simultaneously. carbon dioxide production; critical period; oxygen consumption; respiratory quotient; ventilation PREVIOUSLY, WE CONDUCTED DETAILED, day-to-day studies of various brain stem respiratory nuclei of the rat and found that neurotransmitters and receptors underwent distinct developmental changes. Significantly, at or around postnatal day (P) 12, the expression of excitatory neurotransmitter glutamate and its N-methyl-D-aspartate receptors dropped precipitously, whereas the expression of inhibitory neurotransmitter ␥-aminobutyric acid (GABA), GABA B receptors, and glycine receptors rose sharply (27,30, 61). Concomitantly, there was a sudden fall in cytochrome oxidase activity (27,28, 61), a sensitive indicator of metabolic capacity and neuronal activity (60). We hypothesized that at and around P12 is a sensitive period in the postnatal development of the rat's respiratory control network, when a transient dominance of inhibitory over excitatory neurotransmission renders the animals less capable of overcoming exogenous respiratory stressors. Our subsequent ventilatory studies revealed striking changes in normoxic ventilation ...

show abstract

“…Rats were confined in nose-only tubes modified as body plethysmograph units (Mautz & Bufalino, 1989). Three measurements per hour were made and averaged hourly for 8 rats per atmosphere for 4 h/day on day 1 and 5 of exposure.…”

Section: Methodsmentioning

confidence: 99%

“…These injuries evoke changes in breathing patterns (Mautz et al, 1988;Mautz & Bufalino, 1989;Tepper et al, 1990;Wiester et al, 1995), pulmonary function changes (Horstmann et al, 1990;Folinsbee et al, 1988;Kleinman, 1991), disruption of epithelial cell tight junctions leading to increases in pulmonary epithelial permeability (Bromberg et al, 1991;Bhalla & Crocker, 1987), and changes in functional characteristics of resident bronchoalveolar macrophages (Schlesinger et al, 1992a;Becker et al, 1991;Prasad et al, 1988).…”

mentioning

confidence: 97%

Adaptive and Non-Adaptive Responses in Rats Exposed to Ozone, Alone and in Mixtures, With Acidic Aerosols

Kleinman

Mautz²,

Bjarnason³

1999

Inhalation Toxicology

View full text Add to dashboard Cite

Healthy young adult (300 g) Sprague-Dawley rats were exposed for 1-day or 5-day periods, nose only, to purified air (CA) or four different pollutant atmospheres. Pollutant atmospheres included (a) 0.2 ppm ozone; (b) 0.4 ppm O3; (c) a low concentration mixture of ozone and sulfuric acid-coated carbon particles (0.2 ppm, 100 microg/m(3) and 50 microg/m(3), respectively); and (d) a high-concentration O3 and sulfuric acid-coated carbon particle mixture (0.4 ppm, 500 microg/m(3) and 250 microg/m(3), respectively). Following 1-day exposures to the high O3 concentration, significant (p< or =.05) decreases were observed in respiratory tidal volumes and significant increases were observed in lung inflammatory response. Following 5-day exposures to 0.4 ppm ozone, tidal volumes and lung inflammation were not significantly different from those seen in CA controls. In contrast, following 5-day exposures to the high-concentration O3-particle mixture, lung inflammation was increased significantly relative to that seen after 1-day high concentration mixture exposure or after CA exposure. Macrophage Fc-receptor binding, an important immunological function of macrophages, was significantly depressed after 5-day exposures to either the high- or low-concentration O3-particle mixtures compared to 1-day exposures or to CA. Thus, at the concentrations tested, repeated exposures to O3 produced diminished responses in breathing pattern changes and lung parenchymal injuries compared to acute, single exposures. This diminution was not observed after exposures to mixtures of acidic particles plus ozone. We conclude that mixtures of ozone and acidic particles may alter adaptive mechanisms that have been reported by us and others after repeated exposures to ozone alone.

show abstract

Breathing pattern and metabolic rate responses of rats exposed to ozone

Cited by 41 publications

References 20 publications

Episodic ozone exposure in adult and senescent Brown Norway rats: acute and delayed effect on heart rate, core temperature and motor activity

Episodic ozone exposure in adult and senescent Brown Norway rats: acute and delayed effect on heart rate, core temperature and motor activity

Postnatal development of metabolic rate during normoxia and acute hypoxia in rats: implication for a sensitive period

Adaptive and Non-Adaptive Responses in Rats Exposed to Ozone, Alone and in Mixtures, With Acidic Aerosols

Contact Info

Product

Resources

About