ACUTE COLD EXPOSURE AND THE METABOLISM OF GLUCOSE AND SOME OF ITS PRECURSORS IN THE LIVER OF THE FED AND FASTED SHEEP

Abstract

Measurements of total body O2 consumption, visceral and hepatic blood flow, O2 consumption, exchanges of amino acids, lactate, pyruvate and glucose were made on sheep fed 3-6 h or 21 h before the experiment and exposed for 3 h to a neutral environment (15.degree. C) or a cold environment (0.5-4.degree. C with clipped coat and wind speed 2 m/s). Recent feeding significantly increased the total O2 consumption and the O2 consumption of the viscera and liver. No general release of amino acids from the viscera or uptake by the liver after feeding was detected although the arterial plasma concentration of essential amino acids did increase significantly after feeding. The plasma concentration of most non-essential amino acids also increased except that of glycine, which decreased significantly. Cold exposure increased the total O2 consumption and reduced the respiratory quotient significantly. Release of amino acids from the viscera was stimulated by cold exposure. There was a variable increase in the hepatic uptake of lactate and alanine when the sheep were fasted and cold-exposed. The liver''s glucose output doubled and the blood (arterial) glucose concentration significantly increased in the cold.