Alpha-adrenergic system in the modulation of pancreatic A and B cell function in normal rats
| Autor: | Paolo Filipponi, Carla Mannarelli, F Gregorio, Romeo Pippi, Fausto Santeusanio, Ildo Nicoletti, Celestino Ferrandina |
|---|---|
| Rok vydání: | 1986 |
| Předmět: |
Male
medicine.medical_specialty alpha Epinephrine Adrenergic receptor Endocrinology Diabetes and Metabolism Inbred Strains Adrenergic Biology Arginine Glucagon Islets of Langerhans Endocrinology Internal medicine Insulin Secretion Receptors Internal Medicine Prazosin medicine Animals Insulin drug effects/secretion Receptor Adrenergic alpha-Antagonists Rats Inbred Strains General Medicine Receptors Adrenergic alpha Rats Yohimbine secretion Glucose Adrenergic alpha-Agonists physiology pharmacology Adrenergic alpha-Antagonists pharmacology Animals Arginine pharmacology Epinephrine pharmacology Glucagon secretion Glucose pharmacology Insulin secretion Islets of Langerhans drug effects/secretion Male Rats Rats Inbred Strains Receptors pharmacology medicine.drug |
| Zdroj: | Diabetes Research and Clinical Practice. 2:325-336 |
| ISSN: | 0168-8227 |
| Popis: | The role of the alpha-adrenergic system in the control of pancreatic A and B cell function was investigated in an isolated perfused rat pancreas model. Two experimental procedures were performed. In the first one we evaluated the effects of two distinct concentrations (10(-8) M and 10(-7) M) of five adrenergic substances, with varying degrees of potency on the alpha-adrenergic presynaptic receptor, on insulin (IRI) and glucagon (IRG) release induced by arginine (20 mM) plus glucose (6.6 mM). In the second procedure we studied the effects of the two alpha-blocking agents yohimbine (alpha 2-blocker) and prazosin (alpha 1-blocker) at 10(-7) M on epinephrine-modulated IRI and IRG response to the same combined metabolic stimulus. The inhibitory activity on basal and metabolically induced IRI secretion of the agonists was superimposable on their potency on the presynaptic alpha 2-adrenergic receptors. Similarly, the alpha 1-blocking agent prazosin was less effective than the alpha 2-blocker yohimbine in counteracting the inhibitory effects of epinephrine on basal and arginine plus glucose-induced insulin release. The alpha-cell activity was clearly stimulated by epinephrine, whereas selective alpha-adrenergic drugs showed no significant action on IRG secretion. Both alpha-blockers were ineffective on basal IRG release, while they had some potentiating effect on the epinephrine-induced glucagon release in basal state and during the metabolic stimulus, without a significant difference between the two drugs. We conclude that, at least in the isolated perfused rat pancreas, alpha 2-adrenergic receptors are involved in the inhibition of IRI release induced by catecholamines. On the contrary, the alpha-adrenergic system does not seem to play an essential role in the regulation of IRG secretion; the potentiation of the epinephrine-induced stimulation of A cell function by the alpha-adrenergic blockade could be accounted for by a greater availability of the catecholamine at the beta-receptor binding sites. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|