Barak Otto F, Caljkusic Kresimir, Hoiland Ryan L, Ainslie Philip N, Thom Stephen R, Yang Ming, Jovanov Pavle, Dujic Zeljko
Department of Physiology, Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia.
Faculty of Sports and Physical Education, University of Novi Sad, Novi Sad, Serbia.
Am J Physiol Regul Integr Comp Physiol. 2018 Oct 1;315(4):R759-R767. doi: 10.1152/ajpregu.00412.2017. Epub 2018 Jul 11.
We examined if the diving-induced vascular changes in the peripheral and cerebral circulation could be prevented by oral antioxidant supplementation. Fourteen divers performed a single scuba dive to eighteen meter sea water for 47 min. Twelve of the divers participated in a follow-up study involving breathing 60% of oxygen at ambient pressure for 47 min. Before both studies, participants ingested vitamin C (2 g/day) or a placebo capsule for 6 days. After a 2-wk washout, the study was repeated with the different condition. Endothelium-dependent vasodilator function of the brachial artery was assessed pre- and postintervention using the flow-mediated dilation (FMD) technique. Transcranial Doppler ultrasound was used to measure intracranial blood velocities pre- and 90 min postintervention. FMD was reduced by ∼32.8% and ∼21.2% postdive in the placebo and vitamin C trial and posthyperoxic condition in the placebo trial by ∼28.2% ( P < 0.05). This reduction in FMD was attenuated by ∼10% following vitamin C supplementation in the hyperoxic study ( P > 0.05). Elevations in intracranial blood velocities 30 min after surfacing from diving were reduced in the vitamin C study compared with the placebo trial ( P < 0.05). O breathing had no postintervention effects on intracranial velocities ( P > 0.05). Prophylactic ingestion of vitamin C effectively abrogated peripheral vascular dysfunction following exposure to 60% O but did not abolish the postdive decrease in FMD. Transient elevations of intracranial velocities postdive were reduced by vitamin C. These findings highlight the differential influence of vitamin C on peripheral and cerebral circulations following scuba diving, which are only partly mediated via hyperoxia.
我们研究了口服抗氧化剂补充剂是否可以预防潜水引起的外周和脑循环血管变化。14名潜水员进行了一次水肺潜水，潜入18米深的海水中47分钟。其中12名潜水员参与了一项后续研究，在常压下呼吸60%的氧气47分钟。在两项研究之前，参与者均摄入维生素C（2克/天）或安慰剂胶囊，持续6天。经过2周的洗脱期后，以不同条件重复该研究。干预前后使用血流介导的舒张（FMD）技术评估肱动脉的内皮依赖性血管舒张功能。干预前后使用经颅多普勒超声测量颅内血流速度。在安慰剂和维生素C试验中，潜水后FMD分别降低了约32.8%和约21.2%，在安慰剂试验的高氧条件后降低了约28.2%（P<0.05）。在高氧研究中，补充维生素C后，FMD的这种降低减弱了约10%（P>0.05）。与安慰剂试验相比，维生素C研究中潜水浮出水面30分钟后颅内血流速度的升高有所降低（P<0.05）。高氧呼吸对干预后的颅内速度没有影响（P>0.05）。预防性摄入维生素C有效地消除了暴露于60%氧气后外周血管功能障碍，但并未消除潜水后FMD的降低。维生素C降低了潜水后颅内速度的短暂升高。这些发现突出了维生素C对水肺潜水后外周和脑循环的不同影响，这种影响仅部分通过高氧介导。
