A comparative study of the ventilatory responses of the golden hamster, Mesocricetus auratus and the laboratory rat, Rattus norvegicus, under hypercapnic and/or hypoxic gas mixtures

Abstract

Fossorial mammals are frequently exposed to hypercapnic and/or hypoxic conditions in their burrows. This research compares ventilatory responses of golden hamsters (Mesocricetus auratus) to different ambient respiratory gas concentrations with those of the white rat (Rattus norvegicus). Total body plethysmography was used to measure tidal volume (VT), respiratory frequency (Rf), and minute volume (VE). The respiratory gases had carbon dioxide concentrations ranging from 0 to 790 and oxygen content ranging from 13 to 21%. Both hypercapnic and hypoxic gas mixtures caused hyperventilation in hamsters. The more a gas mixture deviated from normal air, the greater the ventilatory increase. Combining hypercapnic and hypoxic conditions did not potentiate the response. Rats exhibited a greater hyperventilation in response to hypercapnic-hypoxic and hypercapnic gas mixtures than did the hamsters. Hypoxia alone caused a greater response in the hamsters. Greater blood buffering capacity of hamsters offers a possible explanation for the different ventilatory responses observed between these two rodents.