Ventilatory and carotid body responses to acute hypoxia in rats exposed to chronic hypoxia during the first and second postnatal weeks

Publication date: Available online 30 January 2020Source: Respiratory Physiology & NeurobiologyAuthor(s): Ryan W. Bavis, Monata J. Song, Julia P. Smachlo, Alexander Hulse, Holli R. Kenison, Jose N. Peralta, Jennifer T. Place, Sam Triebwasser, Sarah E. Warden, Amy B. McDonoughAbstractChronic hypoxia (CH) during postnatal development causes a blunted hypoxic ventilatory response (HVR) in neonatal mammals. The magnitude of the HVR generally increases with age, so CH could blunt the HVR by delaying this process. Accordingly, we predicted that CH would have different effects on the respiratory control of neonatal rats if initiated at birth versus initiated later in postnatal development (i.e., after the HVR has had time to mature). Rats had blunted ventilatory and carotid body responses to hypoxia whether CH (12% O2) occurred for the first postnatal week (P0 to P7) or second postnatal week (P7 to P14). However, if initiated at P0, CH also caused the HVR to retain the “biphasic” shape characteristic of newborn mammals; CH during the second postnatal week did not result in a biphasic HVR. CH from birth delayed the transition from a biphasic HVR to a sustained HVR until at least P9-11, but the HVR attained a sustained (albeit blunted) phenotype by P13-15. Since delayed maturation of the HVR did not completely explain the blunted HVR, we tested the alternative hypothesis that the blunted HVR was caused by an inflammatory response to CH. Daily administration of the anti-inflammator...
Source: Respiratory Physiology and Neurobiology - Category: Respiratory Medicine Source Type: research