Vianna Lauro C, Deo Shekhar H, Jensen Areum K, Holwerda Seth W, Zimmerman Matthew C, Fadel Paul J
Faculty of Physical Education, University of Brasília, DF, Brazil; Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri;
Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri;
Am J Physiol Heart Circ Physiol. 2015 Apr 1;308(7):H681-7. doi: 10.1152/ajpheart.00343.2014. Epub 2015 Jan 16.
Type 2 diabetes mellitus patients (T2D) have elevated risk of stroke, suggesting that cerebrovascular function is impaired. Herein, we examined dynamic cerebral autoregulation (CA) at rest and during exercise in T2D patients and determined whether underlying systemic oxidative stress is associated with impairments in CA. Middle cerebral artery blood velocity and arterial blood pressure (BP) were measured at rest and during 2-min bouts of low- and high-intensity isometric handgrip performed at 20% and 40% maximum voluntary contraction, respectively, in seven normotensive and eight hypertensive T2D patients and eight healthy controls. Dynamic CA was estimated using the rate of regulation (RoR). Total reactive oxygen species (ROS) and superoxide levels were measured at rest. There were no differences in RoR at rest or during exercise between normotensive and hypertensive T2D patients. However, when compared with controls, T2D patients exhibited lower RoR at rest and during low-intensity handgrip indicating impaired dynamic CA. Moreover, the RoR was further reduced by 29 ± 4% during high-intensity handgrip in T2D patients (0.307 ± 0.012/s rest vs. 0.220 ± 0.014/s high intensity; P < 0.01), although well maintained in controls. T2D patients demonstrated greater baseline total ROS and superoxide compared with controls, both of which were negatively related to RoR during handgrip (e.g., total ROS: r = -0.71, P < 0.05; 40% maximum voluntary contraction). Collectively, these data demonstrate impaired dynamic CA at rest and during isometric handgrip in T2D patients, which may be, in part, related to greater underlying systemic oxidative stress. Additionally, dynamic CA is blunted further with high intensity isometric contractions potentially placing T2D patients at greater risk for cerebral events during such activities.
2型糖尿病患者（T2D）中风风险升高，提示脑血管功能受损。在此，我们检测了T2D患者静息和运动时的动态脑自动调节（CA），并确定潜在的全身氧化应激是否与CA受损有关。分别在7名血压正常和8名高血压的T2D患者以及8名健康对照者静息时，以及在分别以最大自主收缩的20%和40%进行2分钟的低强度和高强度等长握力运动期间，测量大脑中动脉血流速度和动脉血压（BP）。使用调节率（RoR）评估动态CA。在静息时测量总活性氧（ROS）和超氧化物水平。血压正常和高血压的T2D患者在静息或运动时的RoR没有差异。然而，与对照组相比，T2D患者在静息和低强度握力时RoR较低，表明动态CA受损。此外，T2D患者在高强度握力时RoR进一步降低29±4%（静息时为0.307±0.012/s，高强度时为0.220±0.014/s；P<0.01），而对照组中RoR保持良好。与对照组相比，T2D患者表现出更高的基线总ROS和超氧化物水平，两者均与握力时的RoR呈负相关（例如，总ROS：r=-0.71，P<0.05；最大自主收缩的40%）。总体而言，这些数据表明T2D患者在静息和等长握力时动态CA受损，这可能部分与潜在的更大的全身氧化应激有关。此外，高强度等长收缩会使动态CA进一步减弱，可能使T2D患者在此类活动期间发生脑部事件的风险更高。
