Changes in CO2 sensitivity during entrance into, and arousal from hibernation in Ictidomys tridecemlineatus

We examined the time course of the changes in ventilation, O2 consumption rates (\({\dot{\text{V}}}\)o2), CO2 excretion rates, body temperature, and hence the RER and ACR (air convection ratio, ventilation/\({\dot{\text{V}}}\)o2) and the HCVR throughout entrance and arousal into and out of hibernation in 13-lined ground squirrels to confirm this. We observed a significant drop (entrance) and rise (arousal) in the RER produced by hypo- and hyperventilation, respectively. CO2 chemo-sensitivity while the RER was reduced on entrance was blunted and rose late in entrance. On arousal, CO2 chemo-sensitivity was elevated when the RER was elevated and fell immediately after RER returned to normal values. At any givenTb, the HCVR was lower during entrance compared to arousal producing a significant hysteresis. The HCVR, however, was the same at any given\({\dot{\text{V}}}\)o2 during entrance and arousal. These data suggest that both the changes in\({\dot{\text{V}}}\)o2 and in the HCVR are associated with changes in central regulation of the effector limbs establishing steady-state hibernation.
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - Category: Physiology Source Type: research