In vitro Metabolism of 14C-Labelled pyruvate and propionate by ruminant and dog kidney cortex and medulla

Abstract

The pattern of incorporation of 14C into 14CO2 from 14C-labelled pyruvate by dog and sheep kidney cortex and medullary slices and from 14C-labelled propionate by ruminant kidney cortex and medullary slices indicated the greater oxidative capacity of cortex slices in vitro. A major source of carbon dioxide resulting from the metabolism of either cortex or medullary slices was the carboxyl carbon of pyruvate. Dog kidney cortex and medullary slices incorporated greater amounts of 14C from pyruvate-3-14C into total lipid than did the corresponding sheep kidney tissues. The pattern of 14C incorporation into protein from 14C-labelled pyruvate would be compatible with (a) pyruvate transamination to alanine and (b) carboxylation to form oxalacetate with subsequent incorporation of the labelled carbon into aspartate and glutamate. 14CO2 formation by sheep or goat kidney tissues incubated with propionate-3-14C was comparable to 14CO2 formation from pyruvate-3-14C by sheep kidney cortex and medullary slices. Sheep kidney tissues utilized 14C from propionate-3-14C for incorporation into total lipid and protein.