Exercise Reduces Cardiovascular Risk Factors From Constant Stress

Exercise Reduces Cardiovascular Risk Factors from Constant Stress

Newswise — San Diego (April 5, 2016)—Constant stress is associated with signs of poor blood vessel health and increased risk of cardiovascular disease. New research presented today at the Experimental Biology 2016 meeting in San Diego finds that aerobic exercise kept the blood vessels of stressed rats working normally. Blood vessels of exercising stressed rats enlarged more when stimulated than the blood vessels of stressed rats who did not exercise—a sign of better vascular health. Exercise may be an important therapy for promoting cardiovascular health in chronically stressed individuals, the study concludes.

Kent Lemaster, graduate student at West Virginia University, will present “Reversing the Effects of Chronic Stress on the Aorta with Exercise Training” as part of the poster session “Exercise Training Responses” Tuesday, April 5, from 12:45 to 3 p.m. PDT in Exhibit Halls A-D of the San Diego Convention Center.

Full AbstractIndividuals with increased levels of chronic stress have an increased aortic stiffness, which is a strong, independent risk factor for cardiovascular disease. Additionally, chronic stress is associated with a decreased capacity for endothelium­dependent, nitric oxide (NO)­induced vasorelaxation, which may contribute to the aortic stiffness and increased afterload on the heart. Using the unpredictable chronic mild stress protocol (UCMS), lean zucker rats (LZR; healthy rats) develop impaired vascular reactivity in aortic rings concomitant to the onset of chronic stress pathologies. Therapeutic interventions aimed at improving endothelial functioning are therefore considered important avenues for improving CV outcomes in stressed patients. We hypothesized that a chronic aerobic exercise intervention would improve endothelium­ dependent relaxation to methacholine in isolated aortic rings of stressed LZRs. A total of 22 LZRs underwent eight weeks of a treadmill exercise protocol beginning at nine weeks of age. The animals were separated into four groups: sedentary LZR (LZR; n=7); UCMS LZR (UCMS­LZR; n=8); exercise and UCMS (ExUCMS­LZR n=7). Following the intervention, the thoracic aorta was dissected out from each animal and sectioned into rings, some of which were then mounted into an ex vivo wire tension myograph system. The remaining rings were evaluated for NO production in a DAF­FM diacetate assay. Force transduction was used to measure the changes in aortic tension in response to pharmacological agonists. The aortic rings were mechanically set to 1 gram of tension, then pre­constricted using phenylephrine (1x10­6µM), followed by a gradual dilation induced by increasing concentrations of methacholine (1x10­9, 1x10­8, 1x10­7, 1x10-6, 1x10­5 µM respectively). The LZR group demonstrated greater methacholine­induced maximal vasorelaxation compared to the UCMS­LZR group (83% vs. 78%). The ExUCMS­LZR group experienced the greatest maximal dilation (90%) as well as increased values of NO production measured in the DAF assay compared to LZR group and UCMS­LZR group. These results demonstrate that eight weeks of aerobic exercise enhances endothelial bioavailability and/or production of NO, which improves endothelium-dependent vasorelaxation in the aortas of stressed LZRs even more so than the sedentary control. Exercise training may therefore be an important therapy for promoting greater arterial compliance of chronically stressed individuals.

NOTE TO JOURNALISTS: To schedule an interview with a member of the research team, please contact Stacy Brooks at [email protected] or (301) 634-7209.

About Experimental Biology 2016Experimental Biology is an annual meeting comprised of more than 14,000 scientists and exhibitors from six sponsoring societies and multiple guest societies. With a mission to share the newest scientific concepts and research findings shaping clinical advances, the meeting offers an unparalleled opportunity for exchange among scientists from across the United States and the world who represent dozens of scientific areas, from laboratory to translational to clinical research. www.experimentalbiology.org

About the American Physiological Society (APS)APS is a nonprofit organization devoted to fostering education, scientific research and dissemination of information in the physiological sciences. The Society was founded in 1887 and today represents more than 11,000 members and publishes 14 peer-reviewed journals.www.the-aps.org