Lactate release from isolated rat adipocytes: influence of cell size, glucose concentration, insulin and epinephrine.
Release of lactate was studied during in vitro incubations with isolated fat cells. Lactate release increased (approximately 3-fold) with increasing medium glucose concentration (from 3 to 12 mM) in both large and small fat cells. Large fat cells from older, fatter rats, however, released 3-4 times more lactate per cell than small fat cells from young rats when incubated with 3, 6 or 12 mM glucose. Insulin and epinephrine produced a marked stimulation of lactate release in small fat cells, but these hormones had no effect in large fat cells. Lactate accounted for only 10-15% of the glucose metabolized by small fat cells under all incubation conditions but was nearly 40% of glucose utilized by large fat cells at glucose concentrations greater than 6 mM. In conclusion, lactate is a major metabolite of glucose in adipocytes, particularly in the large fat cells. Adipose tissue may therefore be a major site of lactate production, particularly in states of altered glucose metabolism (i.e., hyperglycemia) and obesity.
D000273:Adipose Tissue / Q000166:cytology / Q000378:metabolism*; D000818:Animals; D004837:Epinephrine / Q000494:pharmacology*; D005227:Fatty Acids / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D005990:Glycerol / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology*; D007773:Lactates / Q000378:metabolism*; D019344:Lactic Acid; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
D005227:Fatty Acids; D007328:Insulin; D007773:Lactates; D019344:Lactic Acid; D005947:Glucose; D005990:Glycerol; D004837:Epinephrine