Effects of insulin and a tumour promoter, TPA, on glucose transport and metabolism in retinal pigmented epithelium in vitro.
We have studied the effects of insulin, adenosine and 12-O-tetradecanoylphorbol-13-acetate (TPA) on glucose metabolism of the retinal pigmented epithelial (RPE) cells in vitro. Insulin stimulates glucose transport, glucose oxidation and lipogenesis in RPE cells. TPA at low concentrations of insulin increases the rates of glucose transport and glucose oxidation. Depletion of adenosine in RPE cells by adenosine deaminase increases the rate of both glucose transport and 14CO2 formation and improves insulin-sensitivity of both processes. The effects of TPA on RPE cells cannot be explained by the activation of protein kinase C. An alternative possibility is that the effects of TPA on insulin-stimulated glucose disposal in RPE cells is mediated by a change in adenosine concentration and/or the affinity/number of its receptors.
Budohoski
L
L
Department of Applied Physiology, Medical Research Centre of Polish Academy of Sciences, Warsaw.
Opas
M
M
D015762:2-Chloroadenosine / Q000494:pharmacology; D000241:Adenosine / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002642:Chick Embryo; D004789:Enzyme Activation / Q000187:drug effects; D005947:Glucose / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology*; D010857:Pigment Epithelium of Eye / Q000187:drug effects* / Q000378:metabolism; D011493:Protein Kinase C / Q000187:drug effects; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D007328:Insulin; D015762:2-Chloroadenosine; D011493:Protein Kinase C; D005947:Glucose; D000241:Adenosine; D013755:Tetradecanoylphorbol Acetate