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Hypothermic newborn piglets have a depressed ventilatory response to hypoxia and this may be due to an increase in CNS GABA. In order to evaluate the effects of GABAα receptor blockade on

the ventilatory response to hypoxia in hypothermic piglets, 32 anesthetized, paralyzed, mechanically ventilated newborn piglets (2-7 days) were studied at a brain temperature of 39.0±0.5°C

(Normothermia, NT, n=16) and 34±0.5°C(Hypothermia, HT, n=16). The central respiratory output was evaluated by measuring burst frequency and moving time average area of phrenic nerve

activity. Measurements of minute phrenic output (MPO), arterial blood pressure(ABP), heart rate (HR), oxygen consumption (VdotO2) and arterial blood gases were obtained at room air (RA) and

during 20 min of isocapnic hypoxia(FiO2 =0.10). After 10 min of hypoxia, a bolus injection of 20 μl bicuculline methiodide (BM; 10 μg) or Ringer solution was administered into the cisterna

magna over a 1-min period and the piglets remained in hypoxia for an additional 10 min. Mean±SE values for MPO (au/min) and% change(Δ) from RA (Pre-BM) or 10′ of hypoxia (Post-BM) were as

follows:Table MPO decreased significantly with hypoxia before BM infusion in HT group compared to NT group (P<0.0001). Although there was a significant increase in MPO with hypoxia in

both groups post-BM, this increase was significantly greater in HT group (P<0.008). Changes in VdotO2, ABP, HR, pH, PaO2 and BE with hypoxia were not different between NT and HT groups

post-BM. The cardiorespiratory response to hypoxia was not modified after Ringer solution administration to NT and HT placebo groups. These data suggest that the depression in hypoxic

ventilatory response produced by hypothermia is due to an increase in CNS GABA concentration. AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Dept. of Peds., Div. of Neonatology, Univ. of

Miami School of Med., Miami, FL, USA Qiming Xiao, Cleide Suguihara, Dorothy Hehre, Carlos Devia, Jian Huang & Eduardo Bancalari Authors * Qiming Xiao View author publications You can

also search for this author inPubMed Google Scholar * Cleide Suguihara View author publications You can also search for this author inPubMed Google Scholar * Dorothy Hehre View author

publications You can also search for this author inPubMed Google Scholar * Carlos Devia View author publications You can also search for this author inPubMed Google Scholar * Jian Huang View

author publications You can also search for this author inPubMed Google Scholar * Eduardo Bancalari View author publications You can also search for this author inPubMed Google Scholar

RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Xiao, Q., Suguihara, C., Hehre, D. _et al._ Effects of GABA Receptor Blockade on the Ventilatory Response

to Hypoxia in Hypothermic Newborn Piglets. † 1624. _Pediatr Res_ 41 (Suppl 4), 273 (1997). https://doi.org/10.1203/00006450-199704001-01643 Download citation * Issue Date: 01 April 1997 *

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