The Participation of Carbon Dioxide in the Carbohydrate Cycle

Gluconeogenesis from pyruvate in isolated perfused rat liver

“…When they discovered, in 1935, that bacteria can fix C02 onto pyruvate, Wood and Werkman predicted that such C02-fixing reactions would be found in animal tissues. This was followed by the demonstration that intact rats can incorporate administered bicarbonate-nC into liver glycogen (Solomon et al, 1941;Vennesland et al, 1942). That bicarbonate can serve as a carbon source for glucose synthesis was confirmed by data from liver-slice experiments (Topper and Hastings, 1949;Hiatt et al, 1958).…”

“…the labeling patterns observed in glucose moieties of glycogen derived from pyruvate (Topper and Hastings, 1949) and lactate (Lorber et al, 1950) specifically labeled with isotopic carbon. Randomization of the label in glucose has been used as evidence that oxaloacetate is an obligatory intermediate in gluconeogenesis from pyruvate and, indeed, randomization of the label between the two halves of the four-carbon dicarboxylic acids, oxaloacetate, malate, and aspartate, has been demonstrated to occur rapidly as originally postulated (Solomon et al, 1941; Hoberman and D'Adamo, 1960d;Bloom and Foster, 1962;Haynes, 1965). The routes by which these four-carbon acids can be metabolized in the gluconeogenic process have been investigated (Kalckar, 1939;Utter and Kurahashi, 1954;Utter, 1963;Krebs, 1964;Haynes, 1965;Lardy et al, 1965;Shrago and Lardy, 1966).…”

Hepatic gluconeogenesis. I. Gluconeogenesis in the isolated rat liver. Studies with bicarbonate-14C

“…The randomization of bicarbonate carbon within the fourcarbon dicarboxylic acids (Solomon et al, 1941;Hoberman and D'Adamo, 1960;Bloom and Foster, 1962;Haynes, 1965) explains the retention of no more than half the label in the phosphoenolpyruvate carboxykinase reaction.…”

Tracer isotopes in biochemistry

“…C11 has been used here as a label. When fasted rats were fed lactic acid by stomach tube and injected with the radioactive bicarbonate, there was evidence of the appearance of C11 in glycogen of the liver, but not in muscle glycogen (27). The scientists who conducted these experiments concluded that muscle and liver glycogen were of a different origin and did not exchange between themselves.…”