OXYGEN-CONSUMPTION AND ACID-BASE-BALANCE DURING SHALLOW HYPOTHERMIA IN THE PIGEON

In pigeons, during shallow nocturnal hypothermia induced by food deprivation, body temperature falls to values between 35-degrees-C and 38-degrees-C. Body temperature, oxygen consumption, and arterial blood pH and P(CO2) were recorded during the entrance into such nocturnal hypothermic periods. In vivo pH was kept constant, while in vivo P(CO2) increased slightly during hypothermia. This caused the temperature-corrected value of pH (pH*, measured at 40-degrees-C) to fall by -0.014 units/degrees-C, and the total CO2-content to rise by 3.2 mM, an increase of 16%. These changes in the acid-base balance represent, in effect, a respiratory acidosis that closely parallels the normal buffer line for pigeons. Q10 values, relating oxygen uptake to body temperature, were higher than 4.0 at the very beginning of the entrance into hypothermia, indicating that the metabolic rate was actively inhibited. However, the present results do not indicate any relationship between the acidosis and the inhibition of the metabolic rate.