Temperature Effects on Radiocolloid Uptake by the Isolated Rat Liver

¹ From the U. S. Naval Radiological Defense Laboratory, San Francisco, California

Effect of temperatures between 20° and 38°C on the relation between blood flow and CrPO₄ colloid uptake by the isolated rat liver has been studied. The Q₁₀ for the over-all reaction rate is substantially constant and equal to 1.92 over this range. Theoretical limitations prevent the unambiguous interpretation of this value as a measure of the Q₁₀ of the basic uptake reaction. Hemodynamic data indicate that cooling affects liver blood flow and liver blood distribution primarily, but not exclusively, through increasing blood viscosity. Evidence pointing to possible vasorelaxation under these conditions is mentioned. The application of these results to measurements of liver blood flow in hypothermia in vivo is discussed and the required diagram relating hepatic blood flow with the product of CrPO₄ extraction efficiency and hepatic blood flow for the rat is presented.