Carbohydrate Synthesis in the Isolated Perfused Rat Liver: Role of the Adrenal Cortex

Abstract

The synthesis of glucose by the isolated, perfused rat liver from pyruvate, lactate and alanine has been investigated. When the concentration of pyruvate in the medium was high (initial level 10-2 [image] plus a constant infusion of 1 mg/min.), formation of glucose proceeded rapidly in normal liver and the rate was not altered in livers of adrenalectomized or hypophysectomized animals. At a lower pyruvate concentration (2. 5 x 10-3 [image] plus a constant infusion of 0. 25 mg/min.), gluconeogenesis was reduced; however, the rate in normal and adrenalectomized livers was the same. Glucose production from lactate by normal and adrenalectomized livers was equal to that from pyruvate. When alanine was used as substrate in perfusion of normal liver, glucose synthesis was less than from pyruvate and lactate. Livers of adrenalectomized rats demonstrated a marked reduction in the rate of glucose formation from alanine which could be corrected by adding dexamethasone to the perfusion medium or by injecting the'' hormone into the donor animal prior to hepatectomy. These data suggest that a primary site of action of the adrenal cortical hormones in gluconeogenesis is on conversion of amino acids to pyruvate.