title: Exercise training enhances insulin-stimulated nerve arterial vasodilation in rats with insulin-treated experimental diabetes.
abstract: Insulin stimulates nerve arterial vasodilation through a nitric oxide (NO) synthase (NOS) mechanism. Experimental diabetes reduces vasa nervorum NO reactivity. Studies investigating hyperglycemia and nerve arterial vasodilation typically omit insulin treatment and use sedentary rats resulting in severe hyperglycemia. We tested the hypotheses that 1) insulin-treated experimental diabetes and inactivity (DS rats) will attenuate insulin-mediated nerve arterial vasodilation, and 2) deficits in vasodilation in DS rats will be overcome by concurrent exercise training (DX rats; 75-85% VO2 max, 1 h/day, 5 days/wk, for 10 wk). The baseline index of vascular conductance values (VCi = nerve blood flow velocity/mean arterial blood pressure) were similar (P ≥ 0.68), but peak VCi and the area under the curve (AUCi) for the VCi during a euglycemic hyperinsulinemic clamp (EHC; 10 mU·kg(-1)·min(-1)) were lower in DS rats versus control sedentary (CS) rats and DX rats (P ≤ 0.01). Motor nerve conduction velocity (MNCV) was lower in DS rats versus CS rats and DX rats (P ≤ 0.01). When compared with DS rats, DX rats expressed greater nerve endothelial NOS (eNOS) protein content (P = 0.04). In a separate analysis, we examined the impact of diabetes in exercise-trained rats alone. When compared with exercise-trained control rats (CX), DX rats had a lower AUCi during the EHC, lower MNCV values, and lower sciatic nerve eNOS protein content (P ≤ 0.03). Therefore, vasa nervorum and motor nerve function are impaired in DS rats. Such deficits in rats with diabetes can be overcome by concurrent exercise training. However, in exercise-trained rats (CX and DX groups), moderate hyperglycemia lowers vasa nervorum and nerve function.
authors.affiliation: Neurovascular Research Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada;
authors.forename: T Dylan
authors.initials: TD
authors.lastname: Olver
authors.affiliation: Exercise Biochemistry Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada;
authors.forename: Matthew W
authors.initials: MW
authors.lastname: McDonald
authors.affiliation: Exercise Biochemistry Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada;
authors.forename: Kenneth N
authors.initials: KN
authors.lastname: Grisé
authors.affiliation: Exercise Biochemistry Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada;
authors.forename: Adwitia
authors.initials: A
authors.lastname: Dey
authors.affiliation: Neuromusclar Research Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada;
authors.forename: Matti D
authors.initials: MD
authors.lastname: Allen
authors.affiliation: A. C. Burton Laboratory for Vascular Research, Department of Medical Biophysics, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada;
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Medeiros
authors.affiliation: Department of Electrical and Computer Engineering, Department of Medical Biophysics and Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada;
authors.forename: James C
authors.initials: JC
authors.lastname: Lacefield
authors.affiliation: A. C. Burton Laboratory for Vascular Research, Department of Medical Biophysics, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada;
authors.forename: Dwayne N
authors.initials: DN
authors.lastname: Jackson
authors.affiliation: Neuromusclar Research Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada; Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; and.
authors.forename: Charles L
authors.initials: CL
authors.lastname: Rice
authors.affiliation: Exercise Biochemistry Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada;
authors.forename: C W James
authors.initials: CW
authors.lastname: Melling
authors.affiliation: Exercise Biochemistry Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada;
authors.forename: Earl G
authors.initials: EG
authors.lastname: Noble
authors.affiliation: Neurovascular Research Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology and Pharmacology, The University of Western Ontario, London, Ontario, Canada kshoemak@uwo.ca.
authors.forename: J Kevin
authors.initials: JK
authors.lastname: Shoemaker
mesh_terms: D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology; D004195:Disease Models, Animal; D006943:Hyperglycemia / Q000503:physiopathology; D007328:Insulin / Q000494:pharmacology* / Q000627:therapeutic use*; D009431:Neural Conduction / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000187:drug effects* / Q000502:physiology; D012584:Sciatic Nerve / Q000201:enzymology; D013311:Streptozocin / Q000009:adverse effects; D014650:Vasa Nervorum / Q000187:drug effects* / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects* / Q000502:physiology
chemical_list: D007328:Insulin; D013311:Streptozocin; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III
keywords: Doppler ultrasound; diabetes; exercise; nerve blood flow