title: Hyperglycemia without hyperinsulinemia produces both sympathetic neural activation and vasodilation in normal humans.
abstract: To explore the effects of the acute induction of hyperglycemia on sympathetic activity and vascular function we studied eight normal control subjects (28 +/- 3 years of age). Muscle sympathetic nerve activity (MSNA) and forearm vascular resistance (FVR) were measured before (5.4 +/- 0.2 mmol/L) and during systemic infusion of 20% dextrose with octreotide (250 microg/h) and low dose insulin (4 mU x m(-2) x min(-1)) with 60 min of hyperglycemia (venous plasma glucose, 12.5 +/- 0.6 mmol/L). To control for the effects of hyperosmolarity and volume infusion subjects returned for two control studies with equal volume 20% mannitol and 0.2% saline infusions instead of dextrose infusion. The increase in MSNA during hyperglycemia (178 +/- 48 units) was significantly greater than the increase during mannitol (69 +/- 46 units, p < 0.001) or during 0.2% saline (28 +/- 28 units, p < 0.001). The decreases in FVR after 60 min of hyperglycemia (20 +/- 4 units, p = 0.002) and mannitol (13 +/- 4 units, p = 0.033) were significantly greater than the decrease during saline (0.1 +/- 4 units). The changes in FVR during hyperglycemia and mannitol did not differ. Acute hyperglycemia causes sympathoexcitation and peripheral vasodilation. The vascular effect may be mediated by increased osmolar load.
authors.affiliation: Department of Pediatrics, Clinical Research Center, University of Iowa College of Medicine, Iowa City, USA.
authors.forename: R P
authors.initials: RP
authors.lastname: Hoffman
authors.forename: M
authors.initials: M
authors.lastname: Hausberg
authors.forename: C A
authors.initials: CA
authors.lastname: Sinkey
authors.forename: E A
authors.initials: EA
authors.lastname: Anderson
mesh_terms: D001786:Blood Glucose / Q000378:metabolism; D005260:Female; D005542:Forearm / Q000098:blood supply; D005947:Glucose / Q000008:administration & dosage; D006801:Humans; D006943:Hyperglycemia / Q000503:physiopathology*; D007262:Infusions, Intravenous; D007328:Insulin / Q000494:pharmacology*; D008297:Male; D008353:Mannitol / Q000494:pharmacology; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000294:innervation*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D015282:Octreotide / Q000494:pharmacology*; D012016:Reference Values; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology*; D014655:Vascular Resistance / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*
chemical_list: D001786:Blood Glucose; D007328:Insulin; D008353:Mannitol; D005947:Glucose; D015282:Octreotide