title: Impaired dynamic cerebral autoregulation at rest and during isometric exercise in type 2 diabetes patients.
abstract: 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.
authors.affiliation: Faculty of Physical Education, University of Brasília, DF, Brazil; Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri;
authors.forename: Lauro C
authors.initials: LC
authors.lastname: Vianna
authors.affiliation: Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri;
authors.forename: Shekhar H
authors.initials: SH
authors.lastname: Deo
authors.affiliation: Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri;
authors.forename: Areum K
authors.initials: AK
authors.lastname: Jensen
authors.affiliation: Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri;
authors.forename: Seth W
authors.initials: SW
authors.lastname: Holwerda
authors.affiliation: Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Zimmerman
authors.affiliation: Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri; Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri; and fadelp@health.missouri.edu.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Fadel
mesh_terms: D062186:Arterial Pressure; D001783:Blood Flow Velocity; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation; D002561:Cerebrovascular Disorders / Q000097:blood / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000150:complications / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology*; D003925:Diabetic Angiopathies / Q000097:blood / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D015444:Exercise; D005260:Female; D018737:Hand Strength; D006339:Heart Rate; D006706:Homeostasis; D006801:Humans; D006973:Hypertension / Q000503:physiopathology; D007537:Isometric Contraction; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000503:physiopathology*; D018384:Oxidative Stress; D013481:Superoxides / Q000097:blood; D013997:Time Factors
chemical_list: D013481:Superoxides
keywords: cerebral blood flow; oxidative stress; reactive oxygen species; static handgrip