Ventilation and Respiratory Sensitivity of Euthermic Columbian and Golden-mantled Ground Squirrels (Spermophilus columbianus and Spermophilus lateralis) during the Summer and Winter

Abstract

The first objective of this study was to determine whether species exhibiting different breathing patterns during hibernation have different relative sensitivities to changing blood gases while euthermic. The second was to determine whether the species-specific changes that appear in the relative sensitivities to O₂ and CO₂ as respiratory stimuli in ground squirrels during hibernation are the consequence of changes in ambient temperature and/or seasonal changes as animals prepare for hibernation or whether they are the consequence of entrance into hibernation per se. Toward this end, we examined the changes in ventilatory sensitivity and response thresholds to hypoxia, hypercarbia, and hypoxia plus hypercarbia in summer animals at ambient temperature TA = 22° C and 5° C (acute exposure) as well as in winter animals at TA = 5° C (chronic exposure) during periodic arousal from hibernation in golden-mantled and Columbian ground squirrels. At TA = 22° C, awake, unrestrained golden-mantled and Columbian ground...