期刊
BIOPHYSICAL JOURNAL
卷 99, 期 1, 页码 76-84出版社
CELL PRESS
DOI: 10.1016/j.bpj.2010.04.012
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资金
- National Institutes of Health [RO1-DK46409]
- National Institute of Diabetes and Digestive and Kidney Diseases [F32-DK085960]
- American Heart Association [AHA-0715126]
- National Science Foundation [DMS-0613179, DMS-0917664]
Plasma insulin is pulsatile and reflects oscillatory insulin secretion from pancreatic islets. Although both islet Ca2+ and metabolism oscillate, there is disagreement over their interrelationship, and whether they can be dissociated. In some models of islet oscillations, Ca2+ must oscillate for metabolic oscillations to occur, whereas in others metabolic oscillations can occur without Ca2+ oscillations. We used NAD(P)H fluorescence to assay oscillatory metabolism in mouse islets stimulated by 11.1 mM glucose. After abolishing Ca2+ oscillations with 200 mu M diazoxide, we observed that oscillations in NAD(P)H persisted in 34% of islets (n = 101). In the remainder of the islets (66%) both Ca2+ and NAD(P)H oscillations were eliminated by diazoxide. However, in most of these islets NAD(P)H oscillations could be restored and amplified by raising extracellular KCl, which elevated the intracellular Ca2+ level but did not restore Ca2+ oscillations. Comparatively, we examined islets from ATP-sensitive K+ (K-ATP) channel-deficient SUR1(-/-) mice. Again NAD(P)H oscillations were evident even though Ca2+ and membrane potential oscillations were abolished. These observations are predicted by the dual oscillator model, in which intrinsic metabolic oscillations and Ca2+ feedback both contribute to the oscillatory islet behavior, but argue against other models that depend on Ca2+ oscillations for metabolic oscillations to occur.
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