Dynamic aspects for interislet synchronization of oscillatory insulin secretions

Yao, Nan-Kuang; Chang, Luh‐Maan; Lin, Boniface J.; Kuo, Te Son

doi:10.1152/ajpendo.1997.272.6.e981

Cited by 6 publications

(4 citation statements)

References 23 publications

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“…The synchronization of these islet rhythms is believed to be a prerequisite for producing regular pulses of insulin in the peripheral plasma (14,15). By maintaining intrinsically similar rhythms, the islets of a given mouse would be expected to be more easily entrained to a single pancreatic secretory pattern via a number of putative synchronizing mechanisms, such as an intrapancreatic ganglion pacemaker (33)(34)(35), circulating interislet factors (36), or feedback interactions with the liver (37,38). We note that in vivo experiments to date have only reported fast oscillations of membrane potential and [Ca 2ϩ ] i (39,40), which do not necessarily appear to be synchronized (41).…”

Section: Discussionmentioning

confidence: 99%

Individual Mice Can Be Distinguished by the Period of Their Islet Calcium Oscillations

et al. 2005

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Section: Discussionmentioning

confidence: 99%

Individual Mice Can Be Distinguished by the Period of Their Islet Calcium Oscillations

et al. 2005

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“…However, given that no synchronization of the rapid oscillations in electrical activity of different islets from the same pancreas in vivo has been observed (57), it is less plausible that the rapid secretory events are present in plasma insulin. Another consequence of the rapid passage time of the blood through the pancreas is that blood-borne factors could play a role in coordinating the secretory activities of the islets in the pancreas (10,58). It has been suggested that the intrinsic nervous system of the pancreas is responsible for interislet coordination (13)(14)(15)(16)59), or that the relaying of membrane potential changes among islets via the exocrine tissue is a possible mechanism for synchronizing the islets in the pancreas (10).…”

Section: Discussionmentioning

confidence: 99%

Primary In Vivo Oscillations of Metabolism in the Pancreas

et al. 2002

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The role of metabolism in the generation of plasma insulin oscillations was investigated by simultaneous in vivo recordings of oxygen tension (pO 2 ) in the endocrine and exocrine pancreas and portal blood insulin concentrations in the anesthetized rat. At the start of the experiment, the blood glucose concentration of seven rats was 6.2 ؎ 0.1 mmol/l and the arterial blood pressure was 116 ؎ 5 mmHg. These values did not differ from those obtained at the end of the experiment. Islet pO 2 was measured by impaling superficially located islets with a miniaturized Clark electrode. The pO 2 measurements revealed slow (0.21 ؎ 0.03 min ؊1 ) with superimposed rapid (3.1 ؎ 0.3 min ؊1 ) oscillations. The average pO 2 was 39 ؎ 5 mmHg. Simultaneous recordings of pO 2 in the exocrine pancreas were significantly lower (16 ؎ 6 mmHg), but showed a slow and a rapid oscillatory activity with similar frequencies as seen in the endocrine pancreas. Corresponding measurements of portal insulin concentrations revealed insulin oscillations at a frequency of 0.22 ؎ 0.02 min ؊1 . The results are the first in vivo recordings of an oscillatory islet parameter with a frequency corresponding to that of plasma insulin oscillations; they support a primary role of metabolic oscillations in the induction of plasma insulin oscillations. Diabetes 51:699 -703, 2002 T he regular variations in blood concentrations of insulin, with a typical duration of 5-10 min (1-4), are critical to the hormone's effect in lowering blood glucose (5-10). Despite this importance of insulin oscillations, their generation is still unclear. Oscillations of similar duration have been detected in the secretion of insulin from single isolated islets (11,12). Regular plasma insulin variations are therefore believed to be the result of coordinated secretory activities of the islets of Langerhans in the pancreas (10,13-16). In addition, oscillations in the cytoplasmic Ca 2ϩ concentration ([Ca 2ϩ ] i ) and oxygen tension (pO 2 ) have been shown to be correlated with pulsatile insulin release from isolated islets (12,(17)(18)(19)(20)(21). Therefore, rhythmic changes in ionic fluxes and metabolism are considered to be important for the regulation of plasma insulin oscillations. However, so far these slow in vitro oscillations of [Ca 2ϩ ] i and pO 2 have not been demonstrated in vivo. In the present study, we performed in vivo measurements of pO 2 in rat pancreatic islets and in adjacent exocrine tissue and simultaneously determined portal vein insulin concentrations. RESEARCH DESIGN AND METHODS Materials.Reagents of analytical grade and water purified by a Milli-Q filter (Millipore, Bedford, MA) were used. Tetramethylbenzidine and insulin peroxidase were purchased from Sigma (St. Louis, MO); aprotinin (Trasylol), from Bayer (Leverkusen, Germany); and heparin, from Leo/Løvens (Ballerup, Denmark). The rat insulin standard was obtained from Novo Nordisk (Bagsvaerd, Denmark). IgG-certified microtiter plates were purchased from Nunc (Roskilde, Denmark). The antibodies to insulin...

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“…The second states that individual islets can be entrained by the fluctuations of the common stimulus, glucose [150][151][152][153][154]. Indeed, the entrainability of insulin release by glucose stimulation has been widely observed [155][156][157][158][159][160]. Glucose stimulates islets to release hormones, and then the hormones regulate glucose levels.…”

Section: Network Of Networkmentioning

confidence: 99%

Tripartite cell networks for glucose homeostasis

Song

2019

Phys. Biol.

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Controlling the excess and shortage of energy is a fundamental task for living organisms. Diabetes is a representative metabolic disease caused by the malfunction of energy homeostasis. The islets of Langerhans in the pancreas release long-range messengers, hormones, into the blood to regulate the homeostasis of the primary energy fuel, glucose. The hormone and glucose levels in the blood show rhythmic oscillations with a characteristic period of 5-10 min, and the functional roles of the oscillations are not clear. Each islet has α and β cells that secrete glucagon and insulin, respectively. These two counter-regulatory hormones appear sufficient to increase and decrease glucose levels. However, pancreatic islets have a third cell type, δ cells, which secrete somatostatin. The three cell populations have a unique spatial organization in islets, and they interact to perturb their hormone secretions. The mini-organs of islets are scattered throughout the exocrine pancreas. Considering that the human pancreas contains approximately a million islets, the coordination of hormone secretion from the multiple sources of islets and cells within the islets should have a significant effect on human physiology. In this review, we introduce the hierarchical organization of tripartite cell networks, and recent biophysical modeling to systematically understand the oscillations and interactions of α, β, and δ cells. Furthermore, we discuss the functional roles and clinical implications of hormonal oscillations and their phase coordination for the diagnosis of type II diabetes.

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Dynamic aspects for interislet synchronization of oscillatory insulin secretions

Cited by 6 publications

References 23 publications

Individual Mice Can Be Distinguished by the Period of Their Islet Calcium Oscillations

Individual Mice Can Be Distinguished by the Period of Their Islet Calcium Oscillations

Primary In Vivo Oscillations of Metabolism in the Pancreas

Tripartite cell networks for glucose homeostasis

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