Cutaneous reactive hyperaemia is unaltered by dietary nitrate supplementation in healthy humans
The purpose of this study was to determine whether nitrate supplementation augments cutaneous reactive hyperaemia. Seven participants were tested pre- and postnitrate supplementation (25 ml beetroot juice); participants consumed one shot per day for 3 days. Participants were instrumented with two microdialysis fibres: control (Ringer's solution) and NO synthase inhibition (20 mM L-NAME). Skin blood flow was measured via laser-Doppler flowmetry (LDF). A blood pressure cuff was placed on the experimental arm and inflated to 250 mmHg for 5 mins to occlude arterial inflow. The cuff was released, and the resultant reactive hyperaemia was measured. Blood pressure was continuously measured via plethysmography from a finger on the non-experimental arm. Cutaneous vascular conductance was calculated (LDF/MAP) and normalized to maximal vasodilatation (%CVCmax). Only diastolic blood pressure was reduced following nitrate supplementation (71 ± 2 vs. 66 ± 1 mmHg; P<0·05). There was no effect of nitrate supplementation on peak reactive hyperaemia at control (Pre: 52 ± 3 vs. Post: 57 ± 2%CVCmax) or L-NAME (Pre: 52 ± 2 vs. Post: 59 ± 4%CVCmax) sites. There was no effect of nitrate supplementation on total reactive hyperaemia at either control (Pre: 4197 ± 943 vs. Post: 4523 ± 1040%CVCmax * sec) or L-NAME (Pre: 5108 ± 997 vs. Post: 5694 ± 1002%CVCmax * sec) sites. These data suggest cutaneous reactive hyperaemia is unaffected by dietary nitrate supplementation in healthy humans.