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  • 1
    ISSN: 1432-0428
    Keywords: Insulin secretion ; adrenaline ; noradrenaline ; catecholamines ; dog ; blood glucose ; propranolol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of adrenaline and noradrenaline infusions on pancreaticoduodenal venous insulin output were studied in anaesthetized normal dogs. Two experimental protocols were used. In the first, the dogs had a normal blood glucose level at the start of the catecholamine infusion (normoglycaemic dogs). In the second, the animals were made hyperglycaemic by a continuous glucose infusion (hyperglycaemic dogs). In the normoglycaemic dogs, adrenaline (0.5 μg · kg-1 · min-1) provoked hyperglycaemia accompanied by an increase in insulin output. Noradrenaline (0.5 μg · kg-1 · min-1) also caused an increase in insulin output but without any significant change in blood glucose. In hyperglycaemic dogs, adrenaline (2 μg · kg-1 · min-1) reduced the insulin response and enhanced the hyperglycaemia; noradrenaline (2 μg · kg-1 · min-1) markedly increased the insulin response (+ 2250%) without any significant change in blood glucose. Propranolol (0.3 mg/kg, IV) prevented the increase of insulin induced by noradrenaline. These findings show that, in the normal dog, adrenaline and noradrenaline infusions can produce opposite effects on insulin response depending on the experimental conditions.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0428
    Keywords: Glibenclamide ; hypoglycaemic sulphonamide ; oral antidiabetic substances ; islets of Langerhans ; islet development ; beta cells ; betacytotrophic action ; insulin secretion ; insulin synthesis ; diabetes prevention
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les auteurs ont montré chez la souris que le HB 419 administré chroniquement, stimule le développement des îlots de Langerhans et des cellules bêta. Ce produit est donc doué de l'≪action bêtacytotrophe. Chez le chien normal, l'administration pendant 4 mois de HB 419 a pour effets d'abaisser la glycémie à jeun ainsi que l'ensemble de la courbe de la glycémie nycthémérale.- L'expérimentation effectuée montre que sous l'influence de l'administration prolongée de HB 419, la quantité d'insuline endogène synthétisée et sécrétée en plus de la sécrétion normale est considérable.
    Abstract: Zusammenfassung Die Autoren zeigten an Mäusen, daß chronische Gaben von HB 419 die Entwicklung der Langerhans'schen Inseln und der B-Zellen fördern. Die Substanz besitzt also eine betacytotrophe Wirkung“.Bei normalen Hunden bewirkt Zufuhr von HB 419 über 4 Monate eine Senkung der Nüchternblutzucker-Werte und der 24 Std-Blutzuckerkurven. Unter den gewählten Versuchsbedingungen konnte demonstriert werden, daß es unter dem Einfluß einer Dauerzufuhr von HB 419 zu einer erheblichen Mehrproduktion und Mehrfreisetzung von endogenem Insulin kommt.
    Notes: Summary The authors have demonstrated that HB 419 chronically administered in the mouse, stimulated the development of the islets of Langerhans and particularly that of the beta cells. This substance is thus endowed with a “beta cytotrophic” action. — In the normal dog, HB 419 administered over a four-month period resulted in a decreased fasting glycaemia, as well as a decrease of the entire nyctohemeral glycaemia curve. The experiments carried out showed that under the influence of prolonged HB 419 administration, the amount of endogenous insulin synthesized and secreted over and above the normal secretory level, was considerable.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0428
    Keywords: Insulin secretion ; β-adrenergic receptors ; β-adrenergic blocking agents ; β-adrenergic stimulating agents ; isoprenaline ; propranolol ; practolol ; salbutamol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Il résulte de nos expériences destinées à étudierin vivo, chez le chien anesthésié, le rôle des récepteursβ-adrénergiques impliqués dans l'insulino-sécrétion: 1. que l'isoprénaline (stimulant des récepteurs bêta-adrénergiques) provoque une augmentation importante de la sécrétion d'insuline. — 2. que le propranolol (bloquant des récepteurs bêta-adrénergiques) freine temporairement la sécrétion d'insuline. — 3. quel'isoprénaline, après blocage des récepteurs bêta-adrénergiques par le propranolol, inhibe l'insulino-sécrétion d'une manière puissante et durable. — 4. que le practolol (bloquant plus sélectif des récepteursβ 1) ne s'oppose pas aux effets stimulants de l'isoprénaline qui agit sur les récepteursβ 1 etβ 2, ce qui suggère que le récepteur bêta-adrénergique impliqué dans l'insulinosécrétion est de typeβ 2. — 5. que le salbutamol (stimulant plus sélectif des récepteursβ 2) provoque une abondante sécrétion d'insuline, effet qui se trouve bloqué par le propranolol. Ce fait confirme que le récepteurβ adrénergique impliqué dans l'insulino-sécrétion provoquée par l'isoprénaline est de typeβ 2. -Tous ces faits soulignent l'importance des récepteurs adrénergiquesβ 2 de la cellule bêta des îlots de Langerhans dans le processus d'insulinosécrétion.
    Abstract: Zusammenfassung Wir fanden in unseren Experimenten, die dazu angelegt waren, am anästhesierten Hundin vivo die Rolle derβ-adrenergischen Rezeptoren für die Insulinsekretion zu erforschen: 1. daß Isoprenaline (welches dieβ-adrenergischen Rezeptoren stimuliert), eine starke Erhöhung der Insulinsekretion hervorruft. — 2. daß Propranolol (ein Blocker derβ-adrenergischen Rezeptoren) die Insulinsekretion hemmt. — 3. daß Isoprenaline nach der Blockierung derβ-adrenergischen Rezeptoren durch Propranolol die Insulinsekretion stark, und dauerhaft hemmt. — 4. daß Practolol (welches mehr die Rezeptorenβ 1 hemmt) nicht die Stimulation des Isoprenaline aufhebt, welches sowohl auf dieβ 1 undβ 2 Rezeptoren wirkt. Dieses deutet darauf hin, daß dieβ-adrenergischen Rezeptoren, die bei der Insulinsekretion mitwirken, dem Typβ 2 angehören. — 5. daß Salbutamol (welches mehr dieβ 2-Rezeptoren anregt) eine übermäßige Insulinsekretion bewirkt, die wiederum durch Propranolol zu hemmen ist. Diese Tatsache bestätigt, daß dieβ-adrenerischen Rezeptoren, welche an der durch Isoprenaline hervorgerufenen Insulinsekretion beteiligt sind, dem Typβ 2 angehören. — Alle diese Tatsachen unterstreichen die Bedeutung derβ 2 adrenergischen Rezeptoren derβ-Zelle der Langerhansschen Inseln für den Prozess der Insulinsekretion.
    Notes: Summary As a result of our experiments designed to studyin vivo in the anaesthetized dog, the role of the beta-adrenergic receptors involved in insulin secretion, we have found: 1. that isoprenaline (global stimulator of the beta-adrenergic receptors) provoked a considerable increase in the secretion of insulin. — 2. that propranolol (blocking agent of the beta-adrenergic receptors) partially and temporarily inhibited the secretion of insulin. — 3. that isoprenaline, after blockage of the beta-adrenergic receptors by propranolol, provoked a strong, long-lasting inhibition of insulin secretion. — 4. that practolol (selectivelyβ 1 blocking agent) did not counteract the stimulating effects of isoprenaline (β 1 andβ 2 stimulating agent). This suggests that the beta-adrenergic receptor involved in insulin secretion is of the typeβ 2. — 5. that salbutamol (selectiveβ 2 stimulating agent) provoked an abundant secretion of insulin, an effect which was found to be blocked by propranolol. This last fact confirms that the beta-adrenergic receptor involved in the insulin secretion provoked by isoprenaline is of typeβ 2. — All these findings underline the importance of theβ 2 adrenergic receptors of the beta cell of the islets of Langerhans, in the process of insulin secretion.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0428
    Keywords: Beta cell ; isolated pancreas ; insulin secretion ; acetylcholine ; eserine ; cholinergic receptors ; muscarinic receptors ; atropine ; muscarine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Studies of the role and nature of the cholinergic receptors acting on the secretion of isolated perfused rat pancreas have shown the following: The infusion of acetylcholine at a dose of 2.5 μM in the presence of a concentration of glucose of 1.5 g/1, provoked a first phase of immediate and important stimulation of the secretion of insulin; this initial peak of insulin secretion was followed by a second phase during which a new less intense stimulation occurred; the latter was followed by an inhibition appearing at a time that depended on the pancreas used. At a dose of 0.5 μM of acetylcholine, the first phase of stimulation always appeared; during the second phase some pancreases were inhibited, others remained stimulated. — The peak of insulin secretion obtained by stimulation with acetylcholine during the first phase was dose related. — Eserine intensified the effects of acetylcholine. — The presence of glucose was essential for the insulinsecretory action of acetylcholine. The muscarinic nature of the cholinergic receptors implicated in the secretion of insulin was demonstrated by the use of: — Atropine which completely blocked the effects of acetylcholine, — Muscarine which produced the same effects as acetylcholine on our pancreas preparation, effects which were equally inhibited by atropine. The cholinergic receptors of the endocrine beta cell of the islet of Langerhans of the pancreas are therefore of the muscarinic type.
    Type of Medium: Electronic Resource
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