The existence of an optimal range of cytosolic free calcium for insulin-stimulated glucose transport in rat adipocytes.

摘要: We have examined the effects of extracellular and intracellular Ca2+ concentrations upon basal insulin-stimulated 2-deoxyglucose uptake in isolated rat adipocytes. In absence Ca2+, both glucose were significantly reduced. Insulin-stimulated transport was optimal at 1 2 mM Ca2+. Further increases concentration (3 mM) diminished uptake. When augmented by ionomycin (1 microM), reduced 3 mM. The levels free then measured with indicator fura-2. correlation between magnitude revealed that effect insulin is observed 140 370 nM. At extremes outside this window, low high result cellular responsiveness to insulin. These data suggest calcium may exert a dual role regulation sensitivity First, there must exist minimal promote action. Second, increased provide critical signal for diminution