Submitted on September 26, 2008
Revised on October 28, 2008
Accepted on November 26, 2008
Skin blood flow and nitric oxide during body heating in type 2 diabetes mellitus
Lynn A. Sokolnicki1, Nicholas A. Strom1, Shelly K. Roberts1, Shirley A. Kingsley-Berg1, Ananda Basu1, and Nisha Charkoudian2*
1 Mayo Clinic
2 Mayo Clinic College of Medicine
* To whom correspondence should be addressed. E-mail: charkoudian.nisha{at}mayo.edu.
Individuals with type 2 diabetes mellitus (T2DM) often exhibit microvascular dysfunction which may contribute to impaired thermoregulation, but potential mechanisms remain unclear. Our goals were to quantify skin blood flow responses and nitric oxide-mediated vasodilation during body heating in individuals with T2DM compared to nondiabetic controls of similar age. We measured skin blood flow (laser-Doppler flowmetry) in conjunction with intradermal microdialysis of L-NAME (NO synthase inhibitor) or vehicle during 45 - 60 minutes of whole body heating (WBH) in 10 individuals with T2DM and 14 control subjects. In 6 individuals from each group, we also measured forearm blood flow (FBF) using venous occlusion plethysmography on the contralateral forearm. FBF responses showed diminished absolute cutaneous vasodilation during whole body heating in the T2DM group (PANOVA < 0.01; peak FBF in control: 13.1 ± 1.7 vs. T2DM: 9.0 ± 1.6 ml/100 ml/min). However, the relative contribution of nitric oxide to the cutaneous vasodilator response (expressed as a % of maximal cutaneous vascular conductance) was not different between groups (P > 0.05). We conclude that cutaneous vasodilator responses to whole body heating are decreased in individuals with T2DM, but the contribution of nitric oxide to this smaller vasodilation is similar between T2DM and control individuals. This decrease in cutaneous vasodilation is likely an important contributor to impaired thermoregulation in T2DM.
