Physiological and Genomic Consequences of Intermittent Hypoxia: Selected Contribution: Chemoreflex responses to CO2 before and after an 8-h exposure to hypoxia in humans |
| |
Authors: | Fatemian Marzieh; Robbins Peter A |
| |
Abstract: | The ventilatorysensitivity to CO2, in hyperoxia, is increased after an 8-hexposure to hypoxia. The purpose of the present study was to determinewhether this increase arises through an increase in peripheral orcentral chemosensitivity. Ten healthy volunteers each underwent 8-hexposures to 1) isocapnic hypoxia, with end-tidalPO2 (PETO2) = 55 Torr and end-tidal PCO2(PETCO2) = eucapnia; 2)poikilocapnic hypoxia, with PETO2 = 55 Torr and PETCO2 = uncontrolled;and 3) air-breathing control. The ventilatory response toCO2 was measured before and after each exposure with theuse of a multifrequency binary sequence with two levels of PETCO2: 1.5 and 10 Torr above the normalresting value. PETO2 was held at 250 Torr.The peripheral (Gp) and the central (Gc) sensitivities were calculatedby fitting the ventilatory data to a two-compartment model. There wereincreases in combined Gp + Gc (26%, P < 0.05),Gp (33%, P < 0.01), and Gc (23%, P = not significant) after exposure to hypoxia. There were no significant differences between isocapnic and poikilocapnic hypoxia. We conclude that sustained hypoxia induces a significant increase inchemosensitivity to CO2 within the peripheral chemoreflex. |
| |
Keywords: | |
|
| 点击此处可从《Journal of applied physiology (Bethesda, Md. : 1985)》浏览原始摘要信息 |
| 点击此处可从《Journal of applied physiology (Bethesda, Md. : 1985)》下载免费的PDF全文 |
|