Physiological and genomic consequences of intermittent hypoxia - Selected Contribution: Chemoreflex responses to CO2 before and after an 8-h exposureto hypoxia in humans

Citation
M. Fatemian et Pa. Robbins, Physiological and genomic consequences of intermittent hypoxia - Selected Contribution: Chemoreflex responses to CO2 before and after an 8-h exposureto hypoxia in humans, J APP PHYSL, 90(4), 2001, pp. 1607-1614
Citations number
27
Categorie Soggetti
Physiology
Journal title
JOURNAL OF APPLIED PHYSIOLOGY
ISSN journal
87507587 → ACNP
Volume
90
Issue
4
Year of publication
2001
Pages
1607 - 1614
Database
ISI
SICI code
8750-7587(200104)90:4<1607:PAGCOI>2.0.ZU;2-T
Abstract
The ventilatory sensitivity to CO2, in hyperoxia, is increased after an 8-h exposure to hypoxia. The purpose of the present study was to determine whe ther this increase arises through an increase in peripheral or central chem osensitivity. Ten healthy volunteers each underwent 8-h exposures to 1) iso capnic hypoxia, with end-tidal P-O2 (PETO2) = 55 Torr and end-tidal PCO2 (P ETCO2) = eucapnia; 2) poikilocapnic hypoxia, with PETO2 = 55 Torr and PETCO 2 uncontrolled; and 3) air-breathing control. The ventilatory response to C O2 was measured before and after each exposure with the use of a multifrequ ency binary sequence with two levels of PETCO2: 1.5 and 10 Torr above the n ormal resting value. PETO2 was held at 250 Torr. The peripheral (Gp) and th e central (Gc) sensitivities were calculated by fitting the ventilatory dat a to a two-compartment model. There were increases in combined Gp + Cc (26% , P < 0.05), Gp (33%, P < 0.01), and Gc (23%, P = not significant) after ex posure to hypoxia. There were no significant differences between isocapnic and poikilocapnic hypoxia. We conclude that sustained hypoxia induces a sig nificant increase in chemosensitivity to CO2 within the peripheral chemoref lex.