Four weeks of vitamin D supplementation improves nitric oxide-mediated microvascular function in college-aged African Americans.

Four weeks of vitamin D supplementation improves nitric oxide-mediated microvascular function in college-aged African Americans. Am J Physiol Heart Circ Physiol. 2020 Aug 28;: Authors: Wolf ST, Jablonski NG, Ferguson SB, Alexander LM, Kenney WL Abstract Nitric oxide (NO)-mediated endothelial dysfunction, secondary to increased oxidative stress, presents in young African American (AA) compared to European American (EA) adults, and may be modulated by vitamin D status. We assessed cutaneous microvascular function in 18 young, healthy (21±2 yr; 9 M, 9 F) subjects before (pre: 8 AA, 10 EA) and 13 subjects after (post: 7 AA, 6 EA) four weeks of 2,000 IU/day oral vitamin D supplementation. Serum vitamin D concentrations [25(OH)D] were measured at each visit. Three intradermal microdialysis fibers placed in the ventral forearm were randomized for treatment with 10 μM tempol, 100 μM apocynin, or lactated Ringer's (control). Local heating (39˚C) induced cutaneous vasodilation; red cell flux was measured at each site (laser-Doppler flowmetry) and cutaneous vascular conductance (CVC=flux/MAP) was expressed as a percentage of maximum (28mM sodium nitroprusside+43°C) for each phase of the local heating response. After attaining stable elevated blood flow, 15mM NG-nitro-L-arginine methyl ester (L-NAME; NO synthase inhibitor) was perfused at all sites to quantify the NO contribution to cutaneous vasodilation (%NO), calculated as the difference...
Source: American Journal of Physiology. Heart and Circulatory Physiology - Category: Physiology Authors: Tags: Am J Physiol Heart Circ Physiol Source Type: research