Respiratory adaptations in burrowing pocket gophers from sea level and high altitude

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Abstract
To examine the adaptations to low O2 and high CO2 among fossorial and nonfossorial rodents, hematological parameters were determined for laboratory rats, the valley pocket gopher (Thomomys bottae) from 250 m, and the mountain pocket gopher (T. umbrinus melanotis) from 3150 m. Hematocrit, Hb concentration and O2 capacity were higher in pocket gophers than in rats. Blood PO2 (O2 tension) at 50% saturation and pH 7.4 was 33 mmHg for both gophers and 39 mmHg for rats. Bohr factors for all 3 rodents were similar (-0.55 to -0.61) but buffer value, .DELTA.log PCO2/.DELTA.pH, was -2.54 for T. umbrinus, -1.97 for T. bottae, and -0.98 for Rattus. Concentrations of total acid-soluble phosphates were 50-75% higher in gophers than in rats, while bicarbonate values were within the normal mammalian range. All 3 rot dents had similar myoglobin concentrations in cardiac muscle. Myoglobin concentrations were significantly higher in skeletal muscles (diaphragm, gastrocnemius) of T. umbrinus when compared to T. bottae, and significantly higher in both gophers when compared to rats. These differences may constitute important adaptations to the hypoxia and hypercapnia in burrows; certain of these factors in pocket gophers respond to the additional stress of high altitude hypoxia.

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