Browsing by Author "Phillips, Pamela M."

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    Episodic ozone exposure in adult and senescent Brown Norway rats: Acute and delayed effect on heart rate, core temperature and motor activity
    (Taylor & Francis, 2014-06) Gordon, Christopher J.; Johnstone, Andrew F.M.; Phillips, Pamela M.; MacPhail, Robert C.; Kodavanti, Urmila P.; Ledbetter, Allen D.; Jarema, Kimberly A.; Aydın, Cenk; Uludağ Üniversitesi/Veterinerlik Fakültesi/Temel Bilimler Bölümü.; 7005426982
    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 (O-3) 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 O-3 (6 h/day of 1 ppm O-3 for 2 consecutive days/week for 13 weeks). Acute O-3 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 O-3. Senescent rats were less affected than adults. Acute responses were exacerbated on the second day of O-3 exposure with adults exhibiting greater sensitivity. During recovery following 2 d of O-3, adult and senescent rats exhibited an elevated Tc and HR during the day but not at night, an effect that persisted for at least 48 h after O-3 exposure. MA was elevated in adults but not senescent rats during recovery from O-3. Overall, acute effects of O-3, 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 O-3 in senescent rats may explain the relatively heightened physiological response to O-3 in younger rats.
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    Pulmonary sensitivity to ozone exposure in sedentary versus chronically trained, female rats
    (Taylor & Francis, 2016-03-04) Gordon, Christopher J.; Phillips, Pamela M.; Beasley, Tracey E.; Ledbetter, A.; Snow, Samantha J.; Kodavanti, Urmila P.; Johnstone, Andrew F.; Aydın, Cenk; Uludağ Üniversitesi/Veteriner Fakültesi/Fizyoloji Anabilim Dalı.; 7005426982
    Epidemiological data suggest that a sedentary lifestyle may contribute to increased susceptibility for some environmental toxicants. We developed an animal model of active versus sedentary life style by providing female Sprague-Dawley rats with continuous access to running wheels. Sedentary rats were housed in standard cages without wheels. After training for 12 wks, rats were exposed to 0, 0.25, 0.5 or 1.0ppm ozone [O-3 for 5 h/d, 1 d/wk, for 6 wk (N = 10 per group)]. Body composition (%fat, lean and fluid) was monitored noninvasively over the course of the study. Ventilatory parameters [tidal volume, minute ventilation, frequency and enhanced pause (Penh)] were assessed using whole-body plethysmography prior to O-3 and 24 h after the 5th O-3 exposure. Trained rats lost similar to 2% body fat after 12 wk of access to running wheels. Peak wheel activity was reduced by 40% after exposure to 1.0ppm O-3. After the 5th O-3 exposure, body weight and % fat were reduced in sedentary but not trained rats. Penh was significantly elevated in sedentary but not trained rats the day after exposure to 1.0 ppm O-3. However, lung lavage cell counts and biomarkers of pulmonary inflammation measured 1 day after the final exposure were inconsistently affected by training. Wheel running led to marked physiological responses along with some indication of improved pulmonary recovery from O-3 exposure. However, wheel running with O-3 exposure may also be a detriment for some pulmonary endpoints. Overall, a sedentary lifestyle may increase susceptibility to O-3, but additional studies are needed.