title: Delayed threshold for active cutaneous vasodilation in patients with Type 2 diabetes mellitus.
abstract: Epidemiological evidence suggests decreased heat tolerance in patients with Type 2 diabetes mellitus (T2DM), but it is not known whether the mechanisms involved in thermoregulatory control of skin blood flow are altered in these patients. We tested the hypothesis that individuals with T2DM have a delayed internal temperature threshold for active cutaneous vasodilation during whole body heating compared with healthy control subjects. We measured skin blood flow using laser-Doppler flowmetry (LDF), internal temperature (T or) via sublingual thermocouple, and mean arterial pressure via Finometer at baseline and during whole body heating in 9 T2DM patients and 10 control subjects of similar age, height, and weight. At one LDF site, sympathetic noradrenergic neurotransmission was blocked by local pretreatment with bretylium tosylate (BT) to isolate the cutaneous active vasodilator system. Whole body heating was conducted using a water-perfused suit. There were no differences in preheating T(or) between groups (P > 0.10). Patients with T2DM exhibited an increased internal temperature threshold for the onset of vasodilation at both untreated and BT-treated sites. At BT-treated sites, T or thresholds were 36.28 +/- 0.07 degrees C in controls and 36.55 +/- 0.05 degrees C in T2DM patients (P < 0.05), indicating delayed onset of active vasodilation in patients. Sensitivity of vasodilation was variable in both groups, with no consistent difference between groups (P > 0.05). We conclude that altered control of active cutaneous vasodilation may contribute to impaired thermoregulation in patients with T2DM.
authors.affiliation: Dept. of Physiology and Biomedical Engineering, JO 4-184W, Mayo Clinic College of Medicine, 200 First St. SW, Rochester, MN 55905, USA.
authors.forename: Diane E
authors.initials: DE
authors.lastname: Wick
authors.forename: Shelly K
authors.initials: SK
authors.lastname: Roberts
authors.forename: Ananda
authors.initials: A
authors.lastname: Basu
authors.forename: Paola
authors.initials: P
authors.lastname: Sandroni
authors.forename: Robert D
authors.initials: RD
authors.lastname: Fealey
authors.forename: David
authors.initials: D
authors.lastname: Sletten
authors.forename: Nisha
authors.initials: N
authors.lastname: Charkoudian
mesh_terms: D018674:Adrenergic Antagonists / Q000494:pharmacology; D001831:Body Temperature; D001833:Body Temperature Regulation / Q000502:physiology; D001950:Bretylium Tosylate / Q000494:pharmacology; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D006358:Hot Temperature; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008875:Middle Aged; D012039:Regional Blood Flow; D012867:Skin / Q000098:blood supply* / Q000294:innervation; D013564:Sympathetic Nervous System / Q000187:drug effects; D014664:Vasodilation / Q000502:physiology*
chemical_list: D018674:Adrenergic Antagonists; D001950:Bretylium Tosylate