AJP - Regulatory, Integrative and Comparative Physiology, Vol 268, Issue 1 253-R265, Copyright © 1995 by American Physiological Society
Comparison of ultradian and circadian oscillations of carbon dioxide production by various endotherms
M. Stupfel, V. Gourlet, A. Perramon, P. Merat, G. Putet and L. Court
Environmental Nuisances Research Group, French National Institute of Health and Medical Research, Le Vesinet.
Carbon dioxide emission (VCO2) was computed every 20 min from continuous
CO2 concentration recordings taken during 3-30 consecutive days, in
strictly controlled environmental conditions, in 54 OF1 mice, 99 Japanese
quail, 66 Sprague-Dawley rats, 50 Hartley guinea pigs, 7 chicks, for 7-15
days on 2 Cynomolgus monkeys, and for 24 h on 7 premature infants. This
VCO2 shows circadian and ultradian oscillations that were analyzed for
frequencies and amplitudes in light-dark 12-h alternation (LD 12:12),
continuous light (LL), and continuous dark (DD). Circadians were not always
identified or were often masked in LL or DD (mostly in guinea pigs, quail,
and rats), while ultradians (tau > or = 40 min) were found in all
species, at every time, and in all light regimens. Analysis of variance and
chi 2 show significant (P < 0.001) interspecies differences for
ultradian (1.07 < tau < 1.40 h) intervals and for circadian and
ultradian VCO2 amplitudes. Relationships between ultradian and circadian
VCO2 oscillations differ according to the species, ultradians appearing as
an entity characteristic for each endotherm species.
