Lee Jae-Seok, Stebbins Charles L, Jung Eunji, Nho Hosung, Kim Jong-Kyung, Chang Myoung-Jei, Choi Hyun-Min
Graduate School of Physical Education, Kyung Hee University, Seoul, South Korea; and.
Department of Internal Medicine, Division of Cardiovascular Medicine, University of California at Davis, Davis, California.
Am J Physiol Regul Integr Comp Physiol. 2015 Sep;309(5):R459-66. doi: 10.1152/ajpregu.00099.2015. Epub 2015 Jun 17.
While acute treatment with beetroot juice (BRJ) containing nitrate (NO3 (-)) can lower systolic blood pressure (SBP), afterload, and myocardial O2 demand during submaximal exercise, effects of chronic supplementation with BRJ (containing a relatively low dose of NO3 (-), 400 mg) on cardiac output (CO), SBP, total peripheral resistance (TPR), and the work of the heart in response to dynamic exercise are not known. Thus, in 14 healthy males (22 ± 1 yr), we compared effects of 15 days of both BRJ and nitrate-depleted beetroot juice (NDBRJ) supplementation on plasma concentrations of NOx (NO3 (-)/NO2 (-)), SBP, diastolic blood pressure (DBP), mean arterial pressure (MAP), CO, TPR, and rate pressure product (RPP) at rest and during progressive cycling exercise. Endothelial function was also assessed via flow-mediated dilation (FMD). BRJ supplementation increased plasma NOx from 83.8 ± 13.8 to 167.6 ± 13.2 μM. Compared with NDBRJ, BRJ reduced SBP, DBP, MAP, and TPR at rest and during exercise (P < 0.05). In addition, RPP was decreased during exercise, while CO was increased, but only at rest and the 30% workload (P < 0.05). BRJ enhanced FMD-induced increases in brachial artery diameter (pre: 12.3 ± 1.6%; post: 17.8 ± 1.9%). We conclude that 1) chronic supplementation with BRJ lowers blood pressure and vascular resistance at rest and during exercise and attenuates RPP during exercise and 2) these effects may be due, in part, to enhanced endothelium-induced vasodilation in contracting skeletal muscle. Findings suggest that BRJ can act as a dietary nutraceutical capable of enhancing O2 delivery and reducing work of the heart, such that exercise can be performed at a given workload for a longer period of time before the onset of fatigue.
虽然含有硝酸盐（NO3 (-)）的甜菜根汁（BRJ）急性治疗可降低次最大运动期间的收缩压（SBP）、后负荷和心肌氧需求，但长期补充BRJ（含有相对低剂量的NO3 (-)，400毫克）对心输出量（CO）、SBP、总外周阻力（TPR）以及动态运动时心脏做功的影响尚不清楚。因此，在14名健康男性（22±1岁）中，我们比较了补充15天BRJ和硝酸盐耗尽的甜菜根汁（NDBRJ）对静息和进行性循环运动时血浆NOx（NO3 (-)/NO2 (-)）浓度、SBP、舒张压（DBP）、平均动脉压（MAP）、CO、TPR和速率压力乘积（RPP）的影响。还通过血流介导的血管舒张（FMD）评估内皮功能。补充BRJ使血浆NOx从83.8±13.8μM增加到167.6±13.2μM。与NDBRJ相比，BRJ在静息和运动期间降低了SBP、DBP、MAP和TPR（P<0.05）。此外，运动期间RPP降低，而CO增加，但仅在静息和30%工作量时（P<0.05）。BRJ增强了FMD诱导的肱动脉直径增加（之前：±1.6%；之后：17.8±1.9%）。我们得出结论：1）长期补充BRJ可降低静息和运动时的血压和血管阻力，并在运动期间减弱RPP；2）这些影响可能部分归因于收缩骨骼肌中内皮诱导的血管舒张增强。研究结果表明，BRJ可作为一种膳食营养剂，能够增强氧气输送并减少心脏做功，从而使运动能够在给定工作量下在疲劳发作前持续更长时间。
