Physiological correlates of burrowing in rodents.

1. Blood properties of valley pocket gophers, Thomomys bottae, and laboratory rats, Ratfus norvegicus, were examined to determine blood buffering capabilities. 2. Hematocrit, plasma proteins and inorganic phosphate levels were not significantly different between these species. 3. Oxygen capacity of the pocket gophers, 23.1 vol%, was greater than that of the rats, 20.8 ~ 0 1 % . 4. Bicarbonate concentration of pocket gopher blood, 28.1 mM/l., was significantly greater than that of the rats, 19.8 mM/1. 5. The non-carbonic buffering strength as determined from CO, titration curves of whole blood of pocket gophers, -2.67 logpCO,/pH unit, was greater than that of the rats, 1.39 logpCO,/pH,unit. 6. The greater buffering capacity of pocket gopher blood may account for the reduced sensltlvlty of ventilation rate in response to elevated burrow CO, concentrations.