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Rapid insulin-induced exocytosis in white rat adipocytes

Rapid insulin-induced exocytosis in white rat adipocytes,10.1007/s00424-002-0938-2,Pflugers Archiv-european Journal of Physiology,Helena H. Chowdhury,

Rapid insulin-induced exocytosis in white rat adipocytes   (Citations: 6)
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Insulin is believed to increase glucose permeability of adipocytes by regulating the incorporation of glucose transporters into the plasma membrane by exocytosis. This process involves fusion of membrane-bound cellular compartments with the plasma membrane, thus influencing the plasma membrane area. However, insulin-induced changes in plasma membrane area have not yet been demonstrated. In the present study we monitored fluorescence intensity with a confocal microscope to study the effect of insulin on adipocyte plasma membrane area. After cell isolation and adhesion to a glass cover-slip, adipocytes were stained with the dye FM1-43, a membrane area reporter. At rest, the rate of fluorescence intensity increase was initially high, but gradually stabilized at 2%/min. This steady increase in fluorescence is due to a slow rate of exocytosis coupled to endocytosis, since the removal of FM1-43 from the bath did not abolish FM1-43 fluorescence. Insulin addition caused an abrupt increase of fluorescence intensity of 4%/min, which was significantly higher than in controls. These results suggest rapid, insulin-induced incorporation of new membrane into the plasma membrane by exocytosis.
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    • ...These findings are of interest because it is well accepted that insulin treatment of primary adipocytes increases membrane area in adipocytes (Chowdhury et al. 2002; Coster et al. 2004), indicating a dominant role of exocytosis over endocytosis in insulin-stimulated 3T3-L1...

    Jelena Velebitet al. Rosiglitazone Modulates Insulin-Induced Plasma Membrane Area Changes i...

    • ...The enhanced fluorescence intensity of the muscle fibre boundary, observed in our experiments under the influence of insulin (Figure 2) is consistent with an increase in the surface of the muscle fibre [2, 7]. In the light of present understanding of the effects of insulin, this observation and the demonstrated presence of GLUT4 in these fibres (Fig. 1b) support the conclusion that the increase in surface area is very probably due, at ...
    • ...Innervation is the only means of promoting differentiation of human muscle to the mature, contraction-competent stage under in vitro conditions [1, 6] and the FM1-43 fluorescence-based method has been used successfully in combination with confocal microscopy in our previous studies [2]...

    Helena H. Chowdhuryet al. Insulin-induced exocytosis in single, in vitro innervated human muscle...

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