title: Chronic intermittent hypoxia alters ventilatory and metabolic responses to acute hypoxia in rats.
abstract: We determined the effects of chronic exposure to intermittent hypoxia (CIH) on chemoreflex control of ventilation in conscious animals. Adult male Sprague-Dawley rats were exposed to CIH [nadir oxygen saturation (SpO2), 75%; 15 events/h; 10 h/day] or normoxia (NORM) for 21 days. We assessed the following responses to acute, graded hypoxia before and after exposures: ventilation (V̇e, via barometric plethysmography), V̇o2 and V̇co2 (analysis of expired air), heart rate (HR), and SpO2 (pulse oximetry via neck collar). We quantified hypoxia-induced chemoreceptor sensitivity by calculating the stimulus-response relationship between SpO2 and the ventilatory equivalent for V̇co2 (linear regression). An additional aim was to determine whether CIH causes proliferation of carotid body glomus cells (using bromodeoxyuridine). CIH exposure increased the slope of the V̇e/V̇co2/SpO2 relationship and caused hyperventilation in normoxia. Bromodeoxyuridine staining was comparable in CIH and NORM. Thus our CIH paradigm augmented hypoxic chemosensitivity without causing glomus cell proliferation.
authors.affiliation: John Rankin Laboratory of Pulmonary Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; Department of Orthopedics and Rehabilitation, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; bjmorgan@wisc.edu.
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Morgan
authors.affiliation: John Rankin Laboratory of Pulmonary Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; Department of Orthopedics and Rehabilitation, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin;
authors.forename: Russell
authors.initials: R
authors.lastname: Adrian
authors.affiliation: Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin;
authors.forename: Zun-Yi
authors.initials: ZY
authors.lastname: Wang
authors.affiliation: Department of Health and Human Physiology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, Iowa; and.
authors.forename: Melissa L
authors.initials: ML
authors.lastname: Bates
authors.affiliation: Pharmacy Practice Division, School of Pharmacy, University of Wisconsin, Madison, Wisconsin.
authors.forename: John M
authors.initials: JM
authors.lastname: Dopp
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D002344:Carotid Body / Q000378:metabolism / Q000503:physiopathology; D049109:Cell Proliferation / Q000502:physiology; D002628:Chemoreceptor Cells / Q000378:metabolism / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D000860:Hypoxia / Q000378:metabolism* / Q000503:physiopathology*; D008297:Male; D010100:Oxygen / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012119:Respiration; D014691:Ventilation / Q000379:methods
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen
keywords: carotid body; chemoreceptors; hypoxia; norepinephrine