title: Effects of low-dose L-arginine on insulin-mediated vasodilatation and insulin sensitivity.
abstract: The present study was carried out to evaluate the effect of a low-dose intravenous supplementation of L-arginine on insulin-mediated vasodilatation and insulin sensitivity. The study was performed in healthy subjects (n = 7) and patients with obesity (n = 9) and non-insulin-dependent diabetes mellitus (NIDDM) (n = 9). Insulin-mediated vasodilatation was measured by venous occlusion plethysmography during the insulin suppression test, evaluating insulin sensitivity. Experiments were performed twice in each subject in the presence or absence of a concomitant infusion of L-arginine (0.52 mg kg-1 min-1). L-Arginine restored the imparied insulin-mediated vasodilatation observed in obesity (22.4 +/- 4.1%, P < 0.01 vs. without L-arginine) and NIDDM (20.3 +/- 3.2%, P < 0.01 vs. without L-arginine). In healthy subjects, no effect on insulin mediated-vasodilatation was observed (24.8 +/- 3.1% vs. 21.4 +/- 3.1%). Insulin sensitivity was improved significantly (P < 0.001) in all three groups by infusion of L-arginine. No effect of L-arginine was observed on insulin, insulin-like growth factor I (IGF-I), free fatty acids (FFAs) or C-peptide levels during the insulin suppression test. Our data indicate that defective insulin-mediated vasodilatation in obesity and NIDDM can be normalized by intravenous L-arginine. Furthermore, L-arginine improves insulin sensitivity in obese patients and NIDDM patients as well as in healthy subjects, indicating a possible mechanism that is different from the restoration of insulin-mediated vasodilatation.
authors.affiliation: Department of Internal Medicine, Karl-Franzens University of Graz, Austria.
authors.forename: T C
authors.initials: TC
authors.lastname: Wascher
authors.forename: W F
authors.initials: WF
authors.lastname: Graier
authors.forename: P
authors.initials: P
authors.lastname: Dittrich
authors.forename: M A
authors.initials: MA
authors.lastname: Hussain
authors.forename: B
authors.initials: B
authors.lastname: Bahadori
authors.forename: S
authors.initials: S
authors.lastname: Wallner
authors.forename: H
authors.initials: H
authors.lastname: Toplak
mesh_terms: D000328:Adult; D001120:Arginine / Q000008:administration & dosage*; D002096:C-Peptide / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy / Q000503:physiopathology; D005227:Fatty Acids / Q000097:blood; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000188:drug therapy / Q000503:physiopathology; D014664:Vasodilation / Q000187:drug effects* / Q000502:physiology
chemical_list: D002096:C-Peptide; D005227:Fatty Acids; D007328:Insulin; D007334:Insulin-Like Growth Factor I; D001120:Arginine