Acetoacetate and acetate, intermediates in glutarate catabolism.

The labeling patterns found in tissue glutamate, aspartate, and alanine after administration of glutaric acid-3-Cl4 to male rats (1) indicated that the major catabolic route of glutarate is via acetate (2) and not via a direct conversion to the carbon chain of cu-ketoglutarate (3-5). In further studies on the metabolism of glutarate-3-C14 in rats, we have observed the formation of urinary acetyl groups labeled in the carboxyl position and of urinary acetoacetate labeled chiefly in the carbonyl carbon. Also, rat liver mitochondria have been found to form acetoacetate, labeled predominately in the carbonyl carbon, from glutarate-3-Cr4. To date, our efforts to implicate acetonedicarboxylic acid or /?-hydroxyglutaric acid as intermediates in glutarate catabolism have been unsuccessful.