Adult carotid chemoafferent responses to hypoxia after 1, 2, and 4 wk of postnatal hyperoxia

• Published in: Journal of applied physiology (1985) 2003-09, Vol.95 (3), p.946-952
• Main Authors: Bisgard, G. E, Olson, E. B., Jr, Wang, Z.-Y, Bavis, R. W, Fuller, D. D, Mitchell, G. S
• Format: Article
• Language: English
• Subjects: Animals; Animals, Newborn - physiology; Asphyxia - physiopathology; Biological and medical sciences; Blood Gas Analysis; Blood Pressure - physiology; Blood vessels; Cardiorespiratory control. Arterial mecano- and chemoreceptor; Carotid Body - drug effects; Carotid Body - physiology; Chemoreceptor Cells - physiology; Electrophysiology; Female; Fundamental and applied biological sciences. Psychology; Hydrogen-Ion Concentration; Hyperoxia - pathology; Hyperoxia - physiopathology; Hypoxia - pathology; Hypoxia - physiopathology; Nervous system; Neurons, Afferent - physiology; Organ Size - drug effects; Poisons - pharmacology; Pregnancy; Rats; Rats, Sprague-Dawley; Respiratory system; Rodents; Sodium Cyanide - pharmacology; Time Factors; Vertebrates: respiratory system
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00985.2002

Departments of 1 Comparative Biosciences, 2 Population Health Sciences, and 3 Surgical Sciences, University of Wisconsin, Madison, Wisconsin 53706 Submitted 24 October 2002 ; accepted in final form 12 May 2003 Exposing newborn rats to postnatal hyperoxia (60% O 2 ) for 1-4 wk attenuates the ventilatory and phrenic nerve responses to acute hypoxia in adult rats. The goal of this research was to increase our understanding of the carotid chemoreceptor afferent neural input in this depressed response with different durations of postnatal hyperoxic exposure. Rats were exposed from a few days before birth to 1, 2, or 4 wk of 60% O 2 and studied after 3-5 mo in normoxia. The rats were anesthetized with urethane. Whole carotid sinus nerve (CSN) responses to NaCN (40 µg/kg iv), 10 s of asphyxia and acute isocapnic hypoxia (arterial P O 2 45 Torr) were determined. Mean CSN responses to stimuli after postnatal hyperoxia were reduced compared with controls. Responses in rats exposed to 1 wk of postnatal hyperoxia were less affected than those exposed to 2 and 4 wk of hyperoxia, which were equivalent to each other. These studies illustrate the importance of normoxia during the first 2 wk of life in development of carotid chemoreceptor afferent function. asphyxia; sodium cyanide; carotid body development Address for reprint requests and other correspondence: G. E. Bisgard, Dept. of Comparative Biosciences, Univ. of Wisconsin-Madison, 2015 Linden Dr., Madison, WI 53706 (E-mail: bisgardg{at}svm.vetmed.wisc.edu ).