Carbon sources for D-lactate formation in rat liver.
Carbon sources for D-lactate formation were investigated in vitro using 6,000 x g supernatant of rat liver homogenate and by rat liver perfusion in situ. As carbon sources, L-threonine, glucose, glycerol, acetone, and acetoacetate were tested. Glycerol was the best substrate for D-lactate formation via methylglyoxal in rat liver. Glucose was the second most preferred substrate, while L-threonine, acetone, and acetoacetate were poor substrates for D-lactate formation. Glycerol was several times more effective than normal as a substrate of D-lactate in the supernatants of liver homogenates of diabetic and starved rats, while it was less effective as a substrate of L-lactate. The glycerol kinase [EC 2.7.1.30] activities in livers increased in the diabetic and starved states. These and other results can explain why the plasma concentration of D-lactate increases several-fold after running and why the D-lactate contents in plasma, liver, and skeletal muscle are markedly increases in diabetic and starved rats.
Kondoh
Y
Y
Faculty of Pharmaceutical Sciences, Okayama University.
Kawase
M
M
Hirata
M
M
Ohmori
S
S
D000090:Acetoacetates / Q000378:metabolism; D000096:Acetone / Q000378:metabolism; D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D066298:In Vitro Techniques; D007773:Lactates / Q000096:biosynthesis*; D019344:Lactic Acid; D008099:Liver / Q000378:metabolism*; D008297:Male; D011765:Pyruvaldehyde / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013217:Starvation / Q000378:metabolism; D013912:Threonine / Q000378:metabolism
D000090:Acetoacetates; D007773:Lactates; D000096:Acetone; D013912:Threonine; D019344:Lactic Acid; C016635:acetoacetic acid; D011765:Pyruvaldehyde; D005947:Glucose; D005990:Glycerol