Organ culture of fetal rat pancreas I. Insulin release induced by caffeine and by sugars and some derivatives

Lambert, Ae.; Junod, A.; Stauffcher, Werner; Jeanrenaud, B.; Renold, Albert E.

doi:10.1016/0304-4165(69)90267-0

Cited by 71 publications

(41 citation statements)

References 30 publications

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“…Lambert et al observed that glucosamine is a potent stimulator of embryonic pancreas explants in the presence of caffeine (9). The sudden burst in insulin output seen in the present study after removal of high concentrations of glucosamine from the perfusate might be regarded as a sign of release from inhibition.…”

Section: Resultssupporting

confidence: 57%

“…Theophylline greatly potentiated the effect of glucose, but the pattern of release was not altered qualitatively. The stimulatory action of methyl xanthines on insulin release has been amply documented (7)(8)(9).…”

Section: Resultsmentioning

confidence: 99%

“…However, Lambert et al showed stimulation of insulin release by galactose with explants of fetal pancreas (9) and noted that the addition of caffeine was an absolute requirement for this effect. It is possible that the effect of galactose has been obscured previously because of the use of short periods of stimulation or the use of subthreshold concentrations of glucose which, as shown in these experiments, blocks all but the initial brief response.…”

Section: Resultsmentioning

confidence: 99%

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Kinetics of Insulin Release from the Perfused Rat Pancreas Caused by Glucose, Glucosamine, and Galactose

Landgraf

Matschinsky

1971

Proc. Natl. Acad. Sci. U.S.A.

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Under appropriate conditions, not only glucose but also glucosamine and galactose can serve as potent stimulants for insulin release from the isolated, perfused rat pancreas. Since galactose and, probably, glucosamine are not metabolized in the islets, and since these three compounds have in all likelihood common sites of action, it is postulated that a glucoreceptor of broad specificity is involved in the mechanism of insulin release, and that metabolism of glucose is not an essential part of the releasing action of this sugar.An important but deceptive question about the islets of Langerhans is how glucose stimulates insulin release. The question is important because it concerns a crucial aspect of normal function and of diabetes; it is deceptive because any specific releasing functions of glucose can be easily obscured by the more general role of glucose as a fuel. A promising approach to this difficulty is to compare the effects of glucose with its epimers (e.g., galactose), derivatives (e.g., glucosamine), and other closely related compounds, (e.g., mannoheptulose) and, in this way, to attempt to distinguish release and fuel functions. The perfused pancreas, although technically somewhat demanding (1), seemed an ideal system for such investigations.In this paper we describe the peculiar kinetics of insulin secretion observed when the perfused pancreas of the rat was stimulated by glucose, galactose, or glucosamine alone, by combinations of subthreshold levels of glucose with galactose or glucosamine, and also by combinations of stimulatory amounts of any of the three sugars with theophylline. MATERIALS AND METHODSAll reagents were analytical grade. Dextran The pancreas was isolated and perfused using the procedure described by Grodsky et al. (1) with minor modifications. The animals were fasted overnight, treated with atropine (0.1 mg/kg) intraperitoneal, and anesthetized with pentobarbital (45 mg/kg, intraperitoneal). The pancreas was removed together with the spleen, the stomach, and the proximal part of the duodenum. The celiac axis and the portal vein were cannulated and the organ complex was placed in an incubator at constant temperature (350C). Perfusate was not recycled.The perfusion fluid had the following composition: NaCl, 120 mM; KCl, 4.7 mM; MgSO4, 0.8 mM; CaCl2, 2.5 mM; KH2PO4, 1.2 mM; and NaHCO3, 25 mM. Dextran (8%) was added to provide a colloid osmotic pressure similar to that of serum. 1 hr prior to perfusion, the medium was warmed to 350C and equilibrated with Or-CO2 95:5. The resulting pH was 7.4. The pH changed less than 0.1 unit during one passage through the organ complex. The perfusion pressure varied between 40 and 80 mm of Hg. The average flow rate was 7.0 ml/min and was constant throughout the experiment, which usually lasted 1 hr.After the pancreas was perfused for 10 min with the same medium as used during the control periods of each experiment, the effluent was sampled. Usually three samples were taken as controls. At intervals, indicated in the figures, the perfusate ...

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Section: Resultssupporting

confidence: 57%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Kinetics of Insulin Release from the Perfused Rat Pancreas Caused by Glucose, Glucosamine, and Galactose

Landgraf

Matschinsky

1971

Proc. Natl. Acad. Sci. U.S.A.

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“…However, we did not measure serum concentrations before 4 5 min. Studies of fetal rat ~a n c r e a t i c insulin release conducted in vitro also have shown a delayed and obtunded response t o glucose, and this response can be markedly enhanced by the addition of caffeine or theophylline t o the incubation media (15). Similar enhancement of insulin release by theophylline has been reported in the monkey fetus by Chez et al (1 1).…”

Section: Discussionsupporting

confidence: 53%

Insulin-Glucagon Substrate Interrelations in the Fetal Sheep

et al. 1974

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Extract METHODS AND MATERIALSTwenty-four studies were conducted in 14 sheep fetuses to Fourteen healthy date-bred pregnant ewes with gestational investigate the pancreatic islet a! and /3 cell responses to ages ranging from 100-145 days were studied. The chronic substrate infusions. The studies were conducted between 100 indwelling catheter preparation was utilized and has been days gestation and near term, using indwelling vascular described previously (14). Briefly, a laparotomy through a left catheters for infusions and blood sampling. constant glucose flank incision was performed using spinal anesthesia and infusions (6 mg/kg/min) produced a significant rise in the aseptic technique. Either a jugular vein and carotid artery or a mean concentration of insulin in plasma by 105 min, but no femoral vein and artery were isolated and catheterized, change in glucagon in plasma was observed. Near term (>I35 depending on whether the fetal head or hind limb was most days) the mean plasma insulin increment with constant glucose conveniently exposed. Following catheter placement, the fetus infusion was significantly greater and occurred sooner than in was returned to the uterine cavity and the laparotomy closed.fetuses early in gestation (

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“…This pattern of acute stimulation by leucine, glucagon and theophylline, but not by glucose, is found in fetal islet tissue [14][15][16][17]. Sensitivity to glucagon, theophylline and dibutyryl cyclic AMP, but not to glucose has been reported of a hamster insulinoma [9,10].…”

Section: Discussionmentioning

confidence: 82%

Insulin secretion by a transplantable rat islet cell tumour

et al. 1981

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Summary. Investigation of the subcellular and molecular components of insulin secretion has been made difficult by the small quantities of material available. The recent development of a transplantable rat islet cell tumour of high insulin content and state of differentiation suggested a system more amenable to analysis. To validate the tumour as a model of secretion we have studied its release of insulin. In acute experiments in vitro immunoreactive insulin release was increased by leucine, glucagon, theophylline and dibutyryl cyclic AMP, though not by glucose. Leucine (20 mmol/1) plus theophylline (5 mmol/1) caused an abrupt, sustained and rapidly reversible stimulation of two-to fivefold. The response was inhibited by antagonists of cellular oxidative phosphorylation (cyanide, 2,4--dinitrophenol, antimycin A), calcium flux (EGTA, verapamil, Mg2 § calmodulin (trifluoperazine), microtubules (vinblastine, colchicine) and by adrenaline and somatostatin. These findings suggest that the tumour secretes insulin by an exocytotic mechanism similar to that of normal islet tissue. Key words: Islet cell tumour, B cell, insulin secretionThe pancreatic B cell has proved difficult to investigate at the subcellular and molecular levels. The classical strategy of subcellular fractionation, purification and reassembly has been greatly hindered by the shortage of starting material [3,4]. In this context the description recently of a transplantable rat islet cell tumour is of considerable interest. The tumour contains large amounts of insulin and consists predominantly of well-granulated cells the morphology of which closely resembles that of rat B cells [1,2].That this islet cell tumour might offer a largescale model of insulin secretion is an attractive possibility. Realisation of this potential, however, depends upon establishing that the tumour is indeed capable of the exocytosis of insulin. We here report a series of experiments in which the characteristics of insulin release by the turnout were defined. The effect of putative secretagogues, the dynamics of insulin release, and the influence of potentiators and inhibitors of secretion are described. Materials and MethodsThe islet cell tumour [1, 2] was maintained by serial subcutaneous transplantation within a colony of inbred albino NEDH strain rats [2]. BuffersTissue was handled in a Krebs Ringer solution [5] containing NaC1 115mmol/1, KC1 5.0mmol/1, NaI-ICO 3 24mmol/1, MgC12 1.0 mmol/1 and CaC12 2.5 mmol/1, freshly equilibrated with 5% CO 2 95% 02. Except where specified glucose 2.8 mmol/l, bovine plasma albumin (Armour Pharmaceuticals, Eastbourne, UK) 1.0 mg/ml, and 5.0 mmol/1 each of sodium pyruvate, monosodium glutamate and disodium fumarate were included (using 95 mmol/l NaC1 to maintain the final sodium ion concentration at 139 mmol/ 1). When individual experiments required further additions the osmolality of control buffers was balanced using sucrose.Chemicals were purchased from Fisons Scientific Apparatus, Loughborough, UK and British Drug House Chemicals, Poole,...

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Organ culture of fetal rat pancreas I. Insulin release induced by caffeine and by sugars and some derivatives

Cited by 71 publications

References 30 publications

Kinetics of Insulin Release from the Perfused Rat Pancreas Caused by Glucose, Glucosamine, and Galactose

Kinetics of Insulin Release from the Perfused Rat Pancreas Caused by Glucose, Glucosamine, and Galactose

Insulin-Glucagon Substrate Interrelations in the Fetal Sheep

Insulin secretion by a transplantable rat islet cell tumour

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