A comparison of respiratory adaptations of a semi-fossorial and a surface-dwelling Australian rodent

Respiratory response to inspired CO2 and hematological properties are compared for a semi-fossorial murid, Pseudomys albocinereus, and a surface-dwelling murid, Pseudomys shortridgei. The respiratory response to inspired CO2 is similar for both species and greater than that of a permanently fossorial rodent. This relates to the maintenance of blood pCO2 within narrow limits at CO2 concentrations of less than 5 per cent, and would facilitate O2 transport during periods of activity. Hemoglobin content, hematocrit and red cell count of P. albocinereus are higher than for P. shortridgei, though values of both are typical for mammals of comparable body weight. Hemoglobin of P. albocinereus has a lower P50 than P. shortridgei and this promotes O2 loading during hypoxia. © 1975 Springer-Verlag.