HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 290/6/R1664    most recent 00851.2005v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (6) Citing Articles via Google Scholar Google Scholar Articles by Reeves, S. R. Articles by Gozal, D. Search for Related Content PubMed PubMed Citation Articles by Reeves, S. R. Articles by Gozal, D.

DEVELOPMENTAL PHYSIOLOGY AND PREGNANCY

Early postnatal chronic intermittent hypoxia modifies hypoxic respiratory responses and long-term phrenic facilitation in adult rats

¹Departments of Pediatrics and ²Pharmacology and Toxicology, Kosair Children’s Hospital Research Institute, University of Louisville School of Medicine, Louisville, Kentucky; and ³Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin

Submitted 5 December 2005 ; accepted in final form 27 January 2006

Acute isocapnic intermittent hypoxia elicits time-dependent, serotonin-dependent enhancement of phrenic motor output in anesthetized rats (phrenic long-term facilitation, pLTF). In adult rats, pLTF is enhanced by chronic intermittent hypoxia (CIH). To test the hypothesis that early postnatal CIH induces persistent modifications of ventilation and pLTF, we exposed male Sprague-Dawley rat pups on their first day of life to a CIH profile consisting of alternating room air and 10% oxygen every 90 s for 30 days during daylight hours (RAIH) or to comparable exposures consisting of room air throughout (RARA). One month after cessation of CIH, respiratory responses were recorded using whole body plethysmography, and integrated phrenic nerve activity was recorded in urethane-anesthetized, vagotomized, paralyzed, and ventilated rats at baseline and after exposures to three 5-min hypoxic episodes [inspired O₂ fraction (FI_O2) = 0.11] separated by 5 min of hyperoxia (FI_O2 = 0.5). RAIH rats displayed greater normoxic ventilation and also increased burst frequency compared with RARA rats (P < 0.01). Ventilatory responses to hypoxia and short-term phrenic responses during acute hypoxic challenges were reduced in RAIH rats (P < 0.01). Although pLTF was present in both RAIH and RARA rats, it was diminished in RAIH rats (minute activity: 74 ± 2% in RARA vs. 55 ± 5% in RAIH at 60 min; P < 0.01). Thus we conclude that early postnatal CIH modifies normoxic and hypoxic ventilatory and phrenic responses that persist at 1 mo after cessation of CIH (i.e., metaplasticity) and markedly differ from previously reported increased neural plasticity changes induced by CIH in adult rats.

respiratory control; development; plasticity; metaplasticity

This article has been cited by other articles:

				R. W. Bavis and G. S. Mitchell Long-term effects of the perinatal environment on respiratory control J Appl Physiol, April 1, 2008; 104(4): 1220 - 1229. [Abstract] [Full Text] [PDF]

				C. Julien, A. Bairam, and V. Joseph Chronic intermittent hypoxia reduces ventilatory long-term facilitation and enhances apnea frequency in newborn rats Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2008; 294(4): R1356 - R1366. [Abstract] [Full Text] [PDF]

				H. Gu, M. Lin, J. Liu, D. Gozal, K. E. Scrogin, R. Wurster, M. W. Chapleau, X. Ma, and Z. Cheng Selective impairment of central mediation of baroreflex in anesthetized young adult Fischer 344 rats after chronic intermittent hypoxia Am J Physiol Heart Circ Physiol, November 1, 2007; 293(5): H2809 - H2818. [Abstract] [Full Text] [PDF]

				K. Szdzuy and J. P. Mortola Ventilatory chemosensitivity of the 1-day-old chicken hatchling after embryonic hypoxia Am J Physiol Regulatory Integrative Comp Physiol, October 1, 2007; 293(4): R1640 - R1649. [Abstract] [Full Text] [PDF]