High plasma levels of catecholamines during insulin-induced hypoglycemic stress do not cause beta-adrenergic receptor sequestration. |
| |
Authors: | F Negri M Fratelli P Fratino G Melzi d'Eril G Finardi A De Blasi |
| |
Institution: | Policlinico S. Matteo, Pavia, Italy. |
| |
Abstract: | In the present investigation insulin-induced hypoglycemia was used as a powerful stimulus to rapidly release epinephrine from the adrenal medulla. Insulin injection raised epinephrine 16-fold and doubled norepinephrine plasma levels. The aim of this attempt was to induce beta-adrenergic receptors (beta-ARs) sequestration in vivo on mononuclear leukocytes (MNLs). The number of total and surface beta-ARs was significantly increased 30 minutes after insulin administration, with only partial recovery at 90 minutes. No detectable receptor sequestration was observed: surface receptors were about 90% of total receptors in all the conditions examined. Isoproterenol-stimulated cyclic adenosine monophosphate (cAMP) accumulation was also increased after 30 minutes (+66%) and 90 minutes (+65%) of insulin injection. Basal and forskolin-stimulated intracellular cAMP values were unchanged. We conclude that, even after a strong release of catecholamines, beta-AR redistribution cannot be demonstrated on MNLs. |
| |
Keywords: | |
|
|