Ventilation, CO2 production, and CO2 exposure effects in conscious, restrained CF-1 mice.
Respiratory rate (f), tidal volume (VT) and carbon dioxide production (VECO2) were measured in restrained, conscious CF-1 mice. Mean f +/- S.D. and mean VT +/- S.D. were 270 +/- 8 breaths/min. and 0.123 +/- 0.024 ml (STPD) for male, and 274 +/- 15 breaths/min. and 0.115 +/- 0.023 ml (STPD) for female mice, respectively. VECO2 was obtained from a rebreathing (closed loop) system. The maximum VECO2 (STPD) amounted to 95.5 +/- 15.4 ml/(kg min.) in males and to 72.7 +/- 4.2 ml/(kg min.) in females. The CO2 concentration in the closed loop system increased slowly during a 30 min. rebreathing period and reached a concentration of about 2.7%. No effect was seen on f and on VT. Dynamic (abrupt) exposure up to 10.3% CO2 had no effect on f in male mice, whereas VT increased from 112% (2.3% CO2) to 181% (10.3% CO2). The estimated O2 concentrations decreased from 20.5% to 18.7% with increasing CO2 exposure. The equivalent CO2 experiments with O2 kept at 16% by N2 administration showed that the lower O2 concentration added an additional drive on the respiratory centre.
Danish National Institute of Occupational Health, Copenhagen.
G D
GD
Nielsen
S H
SH
Petersen
A M
AM
Vinggaard
L F
LF
Hansen
P
P
Wolkoff
D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism* / Q000494:pharmacology; D003243:Consciousness; D005260:Female; D008168:Lung / Q000502:physiology; D008297:Male; D051379:Mice; D012119:Respiration / Q000502:physiology*; D013990:Tidal Volume / Q000502:physiology
D002245:Carbon Dioxide