Metabolism of L-lactate by LLC-PK1 renal epithelia

LLC-PK1 renal epithelial cells do not appreciably synthesize D-glucose or glycogen from L-lactate under the conditions described. [U-14C]L-lactate is metabolized to [14C]L-alanine and [14C]L-glutamate. Synthesis of alanine but not glutamate is decreased by the transaminase inhibitor, aminooxyacetate. LLC-PK1 cells also produce unlabeled urea in the presence of [14C]L-lactate. Evidence for net gluconeogenesis has thus not been obtained for this cell line. This is interesting because the LLC-PK1 cells possess an active sugar transport system, and both active sugar transport and gluconeogenesis are localized together in vivo in the proximal tubule.