THE VALIDITY OF RATES OF GLUCOSE APPEARANCE IN THE DOG CALCULATED BY THE METHOD OF SUCCESSIVE TRACER INJECTIONS: II. THE INFLUENCE OF INTERMIXING TIME FOLLOWING TRACER INJECTION

Abstract

Close agreement has been found between calculated rates of C¹²-glucose appearance in, and measured rates of infusion of C¹²-glucose into, the blood plasma of acute surgically eviscerated dogs. The calculated rates were obtained using stated assumptions after allowing intermixing times of 60–120 minutes following single injections of C¹⁴-glucose into the blood stream. Under the above circumstances, the residual body tissues, including the kidneys, appear to add very little C¹²-glucose to that already there when the blood sugar level is maintained at or above normal fasting values. The acute surgical procedures and the removal of adbominal organs result in large decreases in calculated rates of transfer of glucose from the inaccessible to the accessible masses of body glucose. Specific criticisms by others against the validity of tracer-calculated rates of C¹²-glucose appearance in dogs, based on the slow intermixing of injected tracer-glucose with approximately half of the body glucose, are not supported by the findings of this paper.