Compartmentation of glucose and fructose 1,6-bisphosphate metabolism in vascular smooth muscle.
We examined the metabolism of exogenously added 13C-labeled fructose 1,6-bisphosphate (either labeled at the first and sixth carbons or labeled at the first carbon only) and of [2-13C]glucose in well-oxygenated and well-superfused hog carotid artery segments. Exogenously added fructose 1,6-bisphosphate was utilized by hog carotid artery and primarily participated in gluconeogenesis while the production of [3-13C]lactate was not significantly different from zero. When [1,6-13C]fructose 1,6-bisphosphate or [1-13C]fructose 1,6-bisphosphate was utilized individually, gluconeogenic flux occurred without metabolism through aldolase and triosephosphate isomerase resulting in formation of [1,6-13C]-glucose and [1-13C]glucose respectively. When [2-13C]glucose was the sole exogenous substrate, it was utilized and exclusively participated in glycolytic flux with production of [3-13C]lactate and no gluconeogenic flux from the trioses to [5-13C]glucose. When both glucose and fructose 1,6-bisphosphate were provided together as exogenous substrates, glucose still participated exclusively in glycolytic flux with no trioses participating in gluconeogenesis while fructose 1,6-bisphosphate participated in glycolytic flux with [3-13C]lactate production approximately being approximately half of the [1,6-13C]glucose production from [1,6-13C]fructose 1,6-bisphosphate. In the presence of glucose, [1-13C]fructose 1,6-bisphosphate also participated in glycolytic flux and gluconeogenic flux simultaneously. However in the presence of [2-13C]glucose, [1-13C]fructose 1,6-bisphosphate underwent isomerization through the trioses prior to gluconeogenesis since [6-13C]glucose was produced.(ABSTRACT TRUNCATED AT 250 WORDS)
Hardin
C D
CD
Department of Physiology, University of Missouri, Columbia 65212.
Roberts
T M
TM
D000818:Animals; D002247:Carbon Isotopes; D002339:Carotid Arteries; D002451:Cell Compartmentation; D005635:Fructosediphosphates / Q000378:metabolism*; D005943:Gluconeogenesis; D005947:Glucose / Q000378:metabolism*; D006019:Glycolysis; D066298:In Vitro Techniques; D007773:Lactates / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D013552:Swine
D002247:Carbon Isotopes; D005635:Fructosediphosphates; D007773:Lactates; D005947:Glucose; C029063:fructose-1,6-diphosphate