[Hierarchy of control mechanisms of insulin secretion by glucose].
Insulin secretion from pancreatic B-cells is tightly controlled by variations in the plasma concentration of nutrients, in particular glucose. Glucose does not bind to a receptor, but must be metabolized by B-cells to influence the function of the latter. A rise of the ATP/ADP ratio in the cytoplasm closes K(+)-ATP channels in the plasma membrane. This causes depolarization with intermittent opening of Ca2+ channels and generation of a triggering signal: oscillations in the concentration of free cytoplasmic Ca2+. Glucose metabolism also generates a yet unidentified amplifying signal, that augments the efficacy of Ca2+ on the machinery releasing insulin granules. The regulation of insulin secretion may thus be achieved through variations in the amplitude of the indispensable triggering signal or of the important, but insufficient, amplifying signal.
Henquin
J C
JC
Unité d'Endocrinologie et Métabolisme, faculté de Médecine de l'Université catholique de Louvain.
D000244:Adenosine Diphosphate / Q000097:blood; D000255:Adenosine Triphosphate / Q000097:blood; D002118:Calcium / Q000097:blood; D015220:Calcium Channels / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism*; D015221:Potassium Channels / Q000187:drug effects
D015220:Calcium Channels; D007328:Insulin; D015221:Potassium Channels; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D005947:Glucose; D002118:Calcium