In:
American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, American Physiological Society, Vol. 278, No. 1 ( 2000-01-01), p. R282-R286
Kurzfassung:
Mechanisms underlying the circadian rhythm in lung ventilation were investigated. Ten healthy male subjects were studied for 36 h using a constant routine protocol to minimize potentially confounding variables. Laboratory light, humidity, and temperature remained constant, subjects did not sleep, and their meals and activities were held to a strict schedule. Respiratory chemoreflex responses were measured every 3 h using an iso-oxic rebreathing technique incorporating prior hyperventilation. Subjects exhibited circadian rhythms in oral temperature and respiratory chemoreflex responses, but not in metabolic rate. Basal ventilation [i.e., at subthreshold end-tidal carbon dioxide partial pressure ([Formula: see text])] did not vary with time of day, but the ventilatory response to suprathreshold[Formula: see text] exhibited a rhythm amplitude of ∼25%, mediated mainly by circadian variations in the CO 2 threshold for tidal volume. We conclude that the circadian rhythm in lung ventilation is not a simple consequence of circadian variations in arousal state and metabolic rate. By raising the chemoreflex threshold, the circadian timing system may increase the propensity for respiratory instability at night.
Materialart:
Online-Ressource
ISSN:
0363-6119
,
1522-1490
DOI:
10.1152/ajpregu.2000.278.1.R282
Sprache:
Englisch
Verlag:
American Physiological Society
Publikationsdatum:
2000
ZDB Id:
1477297-8
SSG:
12
