ABSTRACT
This chapter examines the changes in breathing pattern and in the ventilatory responses to hypoxic and hypercapnic stimuli in golden-mantled ground squirrels under several conditions known to alter metabolic rate. Compared to many mammals, euthermic golden-mantled ground squirrels, like other fossorial species, exhibit a reduced metabolic rate and resting level of minute ventilation. Their CO2 response threshold is elevated and their ventilatory sensitivity to hypercapnia is also reduced. The correlation between the level of resting minute ventilation and metabolic rate observed during wakefulness, slow wave sleep, hypothermia and hibernation suggests that resting ventilation is tightly regulated by metabolic demands under all these conditions. In association with the fall in metabolic rate which occurs during entrance into hibernation, there is also a fall in ventilation, which gives rise to episodic breathing. Thus the levels of resting ventilation and relative hypoxic sensitivity change in proportion to changes in metabolic rate while breathing pattern and relative hypercapnic sensitivity show further, temperature dependent changes.
