Pulsatile insulin release: role of cytoplasmic Ca2+ oscillations.
Oscillations of plasma insulin are essential for the hypoglycaemic effect of the hormone. Disturbance and partial loss of these oscillations occur during the development of Type 2 diabetes, in association with down-regulation of insulin receptors and insulin resistance. Oscillations with a frequency similar to that of plasma insulin have been observed in the cytoplasmic Ca2+ concentration ([Ca2+]i) of pancreatic beta cells, indicating that the ion plays a role in generating insulin pulses. Studies of individual islets have revealed that oscillations of [Ca2+]i and insulin release are synchronous. However, insulin release is also pulsatile under conditions in which [Ca2+]i is stable. These results support the notion that variations in the ATP/ADP ratio are sufficient to induce pulsatile insulin release. Under physiological conditions, this pulsatility may depend on the synergistic effects of ATP/ADP and [Ca2+]i oscillations.
Bergsten
P
P
Department of Medical Cell Biology, Biomedicum, Uppsala, Sweden. Peter.Bergsten@medcellbiol.uu.se
Lin
J
J
Westerlund
J
J
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D009991:Oscillometry; D012636:Secretory Rate
D007328:Insulin; D002118:Calcium