Protein kinase C activity and lipogenesis from glucose in isolated adipocytes of endotoxemic rats.
The hypothesis was tested that the insulin-like effects of Gram-negative bacterial endotoxins (ET), exerted after in vivo administration on subsequently isolated adipocytes, might be associated with changes in protein kinase C (PKC) activity. The latter is believed to be involved in insulin's mechanism of action on adipocytes. E. coli ET was administered to rats either as a bolus injection (1 mg/100 g bw, in 160-180 g rats, LD50 for 6 hr) or via subcutaneously implanted osmotic pumps (0.1 mg/100 g bw/24 hr, for 30 hr, in 340-380 g rats). Control animals received sterile saline. At 6 hr after bolus injection, and at 30 hr after the onset of ET infusion, the animals were sacrificed and epididymal adipocytes isolated. PKC activity and intracellular distribution were assayed after partial purification on DE-52 cellulose minicolumns. Lipogenesis was measured by [3-3H]-D-glucose incorporation into triglyceride. ET treatment by either mode induced a significant increase (76-80%) in PKC activity. PKC intracellular distribution was altered only in chronically ET-treated rats and was expressed as an increased enzyme activity in the membrane fraction. The increased PKC activity was associated with elevated rates of insulin-stimulated lipogenesis only in young rats. We conclude that in young rats, whose adipocytes display high rates of lipogenesis along with elevated insulin sensitivity, PKC is likely to be one of the possible factors involved in mediation of insulin-like effects of ET.
Spitzer
J A
JA
Department of Physiology, Louisiana State University Medical Center, New Orleans 70112-1393.
Deaciuc
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D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured / Q000187:drug effects; D004195:Disease Models, Animal; D004731:Endotoxins / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism*; D008055:Lipids / Q000096:biosynthesis*; D008297:Male; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012772:Shock, Septic / Q000378:metabolism
D004731:Endotoxins; D008055:Lipids; D011493:Protein Kinase C; D005947:Glucose