Differential vascular reactivity responses acutely following ingestion of a nitrate rich red spinach extract.
BACKGROUND
Inorganic nitrate ingestion has been posited to affect arterial blood pressure and vascular function.


OBJECTIVE
We sought to determine the acute effect of a red spinach extract (RSE) high in inorganic nitrate on vascular reactivity 1-h after ingestion in peripheral conduit and resistance arteries.


METHODS
Fifteen (n = 15; males 8, females 7) apparently healthy subjects (aged 23.1 ± 3.3 years; BMI 27.2 ± 3.7 kg/m2) participated in this crossover design, double-blinded study. Subjects reported to the lab ≥2-h post-prandial and consumed RSE (1000 mg dose; ~90 mg nitrate) or placebo (PBO). Venipuncture was performed on three occasions: baseline, 30-min post-ingestion and between 65 to 75-min post-ingestion. Baseline vascular measurements [i.e., calf venous occlusion plethysmography, brachial artery flow-mediated dilation (FMD)], 30-min of continuous blood pressure (BP) and heart rate (HR) analysis, and follow-up vascular measurements beginning at 40-min post-ingestion were also performed.


RESULTS
Humoral nitrate following RSE ingestion was significantly higher at 30- (+54 %; P = 0.039) and 65 to 75-min post-ingestion compared to baseline (+255 %, P < 0.001) and PBO at the same time points (P < 0.05). No significant changes in BP or HR occurred in either condition. Peak reactive hyperemia (RH) calf blood flow increased significantly (+13.7 %; P = 0.016) following RSE ingestion, whereas it decreased (-14.0 %; P = 0.008) following PBO ingestion. No significant differential FMD responses were detected (P > 0.05), though RH was decreased following the baseline measure in both conditions.


CONCLUSIONS
RSE significantly increased plasma nitrate 30-min post-ingestion, but acute microvascular (i.e., resistance vasculature) reactivity increases were isolated to the lower limb and no appreciable change in brachial artery FMD was observed.
School of Kinesiology, Auburn University, Auburn, AL, 36849, USA.
Cody T
CT
Haun
School of Kinesiology, Auburn University, Auburn, AL, 36849, USA.
Wesley C
WC
Kephart
School of Kinesiology, Auburn University, Auburn, AL, 36849, USA.
Angelia M
AM
Holland
School of Kinesiology, Auburn University, Auburn, AL, 36849, USA.
Christopher B
CB
Mobley
School of Kinesiology, Auburn University, Auburn, AL, 36849, USA.
Anna E
AE
McCloskey
School of Kinesiology, Auburn University, Auburn, AL, 36849, USA.
Joshua J
JJ
Shake
School of Kinesiology, Auburn University, Auburn, AL, 36849, USA.
David D
DD
Pascoe
School of Kinesiology, Auburn University, Auburn, AL, 36849, USA.|Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn Campus, 910 S. Donahue Drive, Auburn, AL, 36832, USA.
Michael D
MD
Roberts
School of Kinesiology, Auburn University, Auburn, AL, 36849, USA. jmartin@auburn.vcom.edu.|Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn Campus, 910 S. Donahue Drive, Auburn, AL, 36832, USA. jmartin@auburn.vcom.edu.
Jeffrey S
JS
Martin
D000284:Administration, Oral; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D001916:Brachial Artery / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D009566:Nitrates / Q000008:administration & dosage* / Q000097:blood; D010936:Plant Extracts / Q000008:administration & dosage / Q000097:blood; D018724:Spinacia oleracea / Q000737:chemistry*; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology*; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*; D055815:Young Adult
D009566:Nitrates; D010936:Plant Extracts
Amaranthus tricolor; Endothelial function; Flow-mediated dilation; Inorganic nitrate; Red spinach; Venous occlusion plethysmography
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