title: The stimulus-secretion coupling of glucose-induced insulin release. XXII. Qualitative and quantitative aspects of glycolysis in isolated islets.
abstract: When isolated islets of Langerhans are suddenly exposed to glucose, the entry of the hexose into islet cells first occurs at a high rate resulting in rapid equilibration of free glucose across the cell membrane; thereafter, the rate of net glucose uptake depends on its metabolism. More than 95% of the glucose taken up by the islets is converted to triosephosphate. The fractional contribution of the sorbitol and pentose-phosphate pathways to such a process does not exceed 10%. The output of lactate from the islets accounts for approximately half of the glycolytic flux. At increasing glucose concentrations up to 4.3 mM, the rate of glycolysis increases towards a first asymptotic value; at higher glucose levels (up to 27.8 mM), a sigmoidal pattern is seen tending towards a second saturation value. The total ATP content of the islets does not correlate with their insulin-secretory activity. It is suggested that, in the process of glucose-induced insulin release, glycolysis may regulate physiological processes possibly located in the micro-environment of the cell boundary.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002245:Carbon Dioxide; D005947:Glucose / Q000378:metabolism* / Q000502:physiology; D006019:Glycolysis; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism*; D007773:Lactates / Q000378:metabolism; D010428:Pentosephosphates / Q000378:metabolism; D051381:Rats; D013012:Sorbitol / Q000378:metabolism; D013403:Sugar Phosphates / Q000378:metabolism
chemical_list: D007328:Insulin; D007773:Lactates; D010428:Pentosephosphates; D013403:Sugar Phosphates; D002245:Carbon Dioxide; D013012:Sorbitol; D000255:Adenosine Triphosphate; D005947:Glucose