Effect of L-alanine infusion on gluconeogenesis and ketogenesis in the rat in vivo.
1. In 48 h-starved 6-week-old rats the 14C incorporation in vivo into blood glucose from a constant-specific-radioactivity pool of circulating [14c]actateconfirmed that lactate is the preferred gluconeogenic substrate. 2. Increasing the blood [alanine] to that occurrring in the fed state increased 14C incorporation into blood glucose 2.3-fold from [14c]alanine and 1.7-fold from [14c]lactate. 3. When the blood [alanine] was increased to that in the fed state, the 14C incorporation into liver glycogen from circulating [14c]alanine or [14c]lactate increased 13.5- and 1.7-fold respectively. 4. The incorporation of 14C into blood acetoacetate and 3-hydroxybutyrate from a constant-specific-radioactivity pool of circulating [14c]oleate was virtually abolished by increasing the blood [alanine] to that existing in the fed state. However, the [acetoacetate] remained unchanged, whereas [3-hydroxybutyrate] decreased, although less rapidly than did its radiochemical concentration. 5. It is concluded that during starvation in 6-week-old rats, the blood [alanine] appears to influence ketogenesis for circulating unesterfied fatty acids and inversely affects gluconeogenesis from either lactate or alanine. A different pattern of gluconeogenesis may exist for alanine and lactate as evidenced by comparative 14C incorporation into liver glycogen and blood glucose.
D000090:Acetoacetates / Q000096:biosynthesis; D000409:Alanine / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D005260:Female; D005943:Gluconeogenesis / Q000187:drug effects*; D006885:Hydroxybutyrates / Q000096:biosynthesis; D007657:Ketone Bodies / Q000096:biosynthesis*; D007773:Lactates / Q000378:metabolism; D008112:Liver Glycogen / Q000378:metabolism; D008297:Male; D009829:Oleic Acids / Q000378:metabolism; D051381:Rats; D013217:Starvation
D000090:Acetoacetates; D001786:Blood Glucose; D006885:Hydroxybutyrates; D007657:Ketone Bodies; D007773:Lactates; D008112:Liver Glycogen; D009829:Oleic Acids; D000409:Alanine