The role of leucine in ketogenesis in starved rats.
The quantitative significance of the conversion in vivo of L-[U-14C]leucine to ketone bodies was determined in rats starved for 3 or 48 h. In animals starved for 3 h, 4.4% of ketone-body carbon is derived from the metabolism of leucine, and in rats starved for 48 h the corresponding value is 2.3%. This conversion occurs rapidly, and the specific radioactivity of ketone bodies in blood is maximal at 2 min after the intravenous injection of labelled leucine for both periods of starvation. The flux of leucine in the blood is 1.01 and 1.04 mumol/min per 100 g body wt. respectively for animals starved for 3 and 48 h. The specific radioactivity of blood ketone bodies was compared at 2 min after the injection of labelled leucine, lysine and phenylalanine. The specific radioactivity was 4-5 fold higher with leucine than with lysine or phenylalanine.
D000818:Animals; D007657:Ketone Bodies / Q000096:biosynthesis* / Q000097:blood; D007930:Leucine / Q000097:blood / Q000378:metabolism*; D010649:Phenylalanine / Q000378:metabolism; D051381:Rats; D013217:Starvation / Q000097:blood / Q000378:metabolism*; D013997:Time Factors
D007657:Ketone Bodies; D010649:Phenylalanine; D007930:Leucine