The incorporation of carbon dioxide into milk citrate in the isolated perfused goat udder |
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| Authors: | D. C. Hardwick |
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| Affiliation: | Agricultural Research Council Institute of Animal Physiology, Babraham, Cambridge |
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| Abstract: | 1. Isolated perfused goat udders supplied with glucose, acetate and amino acids were infused for several hours with NaH14CO3. 2. Lactose, milk-fat fatty acids and glycerol had very little radioactivity. The specific radioactivity (counts./min./mg. of C) of milk citrate was 9–16% that of the carbon dioxide in the perfusion fluid and 19% that estimated for tissue carbon dioxide. The specific radioactivity of tissue citrate resembled that of milk citrate. 3. The radioactivity in citrate was predominantly in C-6, suggesting some carboxylation of α-oxoglutarate in addition to carboxylation of C3 compounds. 4. [1-14C]Glutamate was infused in a similar experiment, and milk citrate radioactivity was predominantly in C-1+C-5. 5. The results are discussed in relation to the contribution of glucose and acetate carbon to citrate. The implications of the carboxylation of α-oxoglutarate are considered. |
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