In the present studies, we used a recently validated canine model to determine 1) if glucose ingestion stimulates insulin secretion by amplifying the pulsatile component of insulin release, and if so, 2) whether this effect is achieved preferentially through burst mass or frequency modulation, and 3) if the mechanism of incretin effect of insulin secretion is mediated via the pulsatile mode of secretion. We report that 30 g of glucose ingestion stimulates an ∼ 550% increase in the overall rate of insulin secretion (1.8 ± 0.2 to 11.6 ± 1.5 pmol.kg−1 · min−1), which is achieved via an ∼ 400% increase in the mass of insulin secreted per burst (202 ± 38 to 1,003 ± 147 pmol/pulse, P < 0.001) and a ∼ 40% increase in burst frequency (8.7 ± 0.5 to 12.3 ± 0.6 pulse/h, P < 0.001). Of the insulin secreted after glucose ingestion, 68% (±4) was released in discrete secretory bursts. Further analyses showed that the incretin effect of ingested (GPO) versus infused glucose (GIV) is achieved through regulation of pulsatile insulin secretion. Glucose ingestion led to an ∼ 70% greater rate of insulin secretion than intravenous glucose delivery (10.0 ± 1.6 vs. 5.9 ± 0.9 pmol.kg−1 · min−1, P < 0.005, GPO vs. GIV). This incretin effect was achieved by the specific mechanism of an ∼ 70% greater pulse mass (930 ± 196 vs. 558 ± 97 pmol/pulse, P < 0.02, GPO vs. GIV) but with a comparable pulse frequency (13.1 ± 0.9 vs. 12.0 ± 0.5 pulses/h, P = 0.14, n = 9 dogs, GPO vs. GIV). We conclude that in vivo glucose regulates overall insulin secretion almost exclusively by amplification of the pulsatile mode of insulin secretion, and that the incretin effect is achieved by preferential enhancement of insulin secretory burst mass.
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October 01 1996
Effects of Glucose Ingestion Versus Infusion on Pulsatile Insulin Secretion: The Incretin Effect Is Achieved by Amplification of Insulin Secretory Burst Mass
Niels Pørksen;
Niels Pørksen
Endocrine Research Unit, Mayo Clinic
Rochester, Minnesota
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Stephen Munn;
Stephen Munn
Division of Transplant Surgery, Mayo Clinic
Rochester, Minnesota
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Jeffery Steers;
Jeffery Steers
Division of Transplant Surgery, Mayo Clinic
Rochester, Minnesota
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Johannes D Veldhuis;
Johannes D Veldhuis
Department of Medicine and Center for Biological Timing
Charlottesville, Virginia
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Peter C Butler
Peter C Butler
Endocrine Research Unit, Mayo Clinic
Rochester, Minnesota
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Address correspondence and reprint requests to Prof. Peter C. Butler, Department of Medicine, University of Edinburgh, Western General Hospital, Crewe Rd., Edinburgh, Scotland.
Diabetes 1996;45(10):1317–1323
Article history
Received:
January 09 1996
Revision Received:
May 07 1996
Accepted:
May 07 1996
PubMed:
8826965
Citation
Niels Pørksen, Stephen Munn, Jeffery Steers, Johannes D Veldhuis, Peter C Butler; Effects of Glucose Ingestion Versus Infusion on Pulsatile Insulin Secretion: The Incretin Effect Is Achieved by Amplification of Insulin Secretory Burst Mass. Diabetes 1 October 1996; 45 (10): 1317–1323. https://doi.org/10.2337/diab.45.10.1317
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