Sprick Justin D, Rickards Caroline A
Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, Fort Worth, Texas.
Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, Fort Worth, Texas
Am J Physiol Regul Integr Comp Physiol. 2017 Nov 1;313(5):R497-R506. doi: 10.1152/ajpregu.00111.2017. Epub 2017 Aug 23.
Remote ischemic preconditioning (RIPC) can attenuate tissue damage sustained by ischemia-reperfusion injury. Blood flow restriction exercise (BFRE) restricts blood flow to exercising muscles. We implemented a novel approach to BFRE with cyclical bouts of blood flow restriction-reperfusion, reflecting the RIPC model. A concern about BFRE, however, is potential amplification of the exercise pressor reflex, which could be unsafe in at-risk populations. We hypothesized that cyclical BFRE would elicit greater increases in sympathetic outflow and arterial pressure than conventional exercise (CE) when performed at the same relative intensity. We also assessed the cerebrovascular responses due to potential implementation of BFRE in stroke rehabilitation. Fourteen subjects performed treadmill exercise at 65-70% maximal heart rate with and without intermittent BFR (4 × 5-min intervals of bilateral thigh-cuff pressure followed by 5-min reperfusion periods). Mean arterial pressure (MAP), plasma norepinephrine (NE), and middle and posterior cerebral artery velocities (MCAv and PCAv) were compared between trials. As expected, BFRE elicited higher concentration NE compared with CE (1249 ± 170 vs. 962 ± 114 pg/ml; = 0.06). Unexpectedly, however, there were no differences in MAP between conditions (overall = 0.33), and MAP was 4-5 mmHg lower with BFRE versus CE during the reperfusion periods ( ≤ 0.05 for reperfusion and ). There were no differences in MCAv or PCAv between trials ( ≥ 0.22), suggesting equivalent cerebrometabolic demand. The exaggerated sympathoexcitatory response with BFRE was not accompanied by higher MAP, likely because of the cyclical reperfusions. This cyclical BFRE paradigm could be adapted to cardiac or stroke rehabilitation, where exercising patients could benefit from the cardio and cerebro protection associated with RIPC.
远程缺血预处理（RIPC）可减轻缺血再灌注损伤所导致的组织损伤。血流限制运动（BFRE）会限制流向运动肌肉的血流。我们采用了一种新颖的BFRE方法，即进行周期性的血流限制-再灌注，这反映了RIPC模型。然而，对BFRE的一个担忧是运动压力反射可能会增强，这对高危人群可能不安全。我们假设，在相同相对强度下进行时，周期性BFRE比传统运动（CE）会引起更大的交感神经输出增加和动脉压升高。我们还评估了由于BFRE在中风康复中的潜在应用而产生的脑血管反应。14名受试者在最大心率的65%-70%下进行跑步机运动，有或没有间歇性血流限制（双侧大腿袖带压力为4个5分钟间隔，随后是5分钟的再灌注期）。在各试验之间比较平均动脉压（MAP）、血浆去甲肾上腺素（NE）以及大脑中动脉和大脑后动脉速度（MCAv和PCAv）。正如预期的那样，与CE相比，BFRE引起的NE浓度更高（1249±170对962±114 pg/ml；P = 0.06）。然而，出乎意料的是，不同条件下的MAP没有差异（总体P = 0.33），并且在再灌注期，BFRE时的MAP比CE时低4-5 mmHg（再灌注期P和P≤0.05）。各试验之间的MCAv或PCAv没有差异（P≥0.22），表明脑代谢需求相当。BFRE时交感神经兴奋性反应增强，但并未伴有更高的MAP，这可能是由于周期性再灌注所致。这种周期性BFRE模式可适用于心脏或中风康复，在此过程中，运动的患者可从与RIPC相关的心脏和脑保护中获益。
