AJP - Regulatory, Integrative and Comparative Physiology, Vol 241, Issue 5 264-R266, Copyright © 1981 by American Physiological Society
Metabolic contribution of CO2 to the "group effect"
E. H. Schlenker, D. Carlson and C. F. Herreid 2nd
Metabolic rates (VCO2) were determined in 22 mice. Subsequently 11 of the
mice were placed into separate metabolic chambers. Each chamber was
connected to one other metabolic chamber containing one mouse. The
metabolic rates of the 11 "donor" and the 11 "'recipient" mice were
measured. Afterwards the direction of airflow was reversed so that the
previous donor became the recipient mouse and the previous recipient became
the donor. Again VCO2 was measured. When the mice were donors, VCO2 = 2.75
+/- 1.0 ml CO2 . g-1 . h-1, whereas when recipients, VCO2 = 1.9 +/- 1.0 ml
CO2 . g-1 . h-1 (P less than 0.01). Eleven of the mice were then made
anosmic using an intranasal instillation of 5% ZnSO4. Anosmia was confirmed
behaviorally. The metabolic rates of the anosmic and control mice were
again determined when each was a donor and a recipient. VCO2 dropped from
3.1 to 1.8 ml CO2 . g-1 . h-1 from donor status to recipient status.
Finally, VCO2 was determined when all 22 mice were exposed to 0.05% CO2 or
0.2% CO2 in air (the level of CO2 in the exhaust air of donor mice). VCO2
dropped from 3.0 +/- 0.38 on 0.05% CO2 to 1.7 +/- 1.01 on 1.01 ml CO2 . g-1
. h-1 on 0.2% CO2 in the anosmic group and from 2.9 +/- 0.29 to 1.91 +/-
0.51 ml CO2 . g-1 . h-1 in the control group when exposed to the same
gases. These experiments suggest that the airborne factor emanating from
the donor chambers was acting systematically and not via the olfactory
system. This factor may be a low level of CO2.
