{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,22]],"date-time":"2026-10-22T20:40:15Z","timestamp":1792701615062,"version":"4.5.0"},"reference-count":61,"publisher":"American Physiological Society","issue":"5","funder":[{"DOI":"10.13039\/100000050","name":"HHS | NIH | National Heart, Lung, and Blood Institute (NHBLI)","doi-asserted-by":"publisher","award":["HL118313"],"award-info":[{"award-number":["HL118313"]}],"id":[{"id":"10.13039\/100000050","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000738","name":"U.S. Department of Veterans Affairs (VA)","doi-asserted-by":"publisher","award":["RX001311"],"award-info":[{"award-number":["RX001311"]}],"id":[{"id":"10.13039\/100000738","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000738","name":"U.S. Department of Veterans Affairs (VA)","doi-asserted-by":"publisher","award":["RX001418"],"award-info":[{"award-number":["RX001418"]}],"id":[{"id":"10.13039\/100000738","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000738","name":"U.S. Department of Veterans Affairs (VA)","doi-asserted-by":"publisher","award":["RX000182"],"award-info":[{"award-number":["RX000182"]}],"id":[{"id":"10.13039\/100000738","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["American Journal of Physiology-Regulatory, Integrative and Comparative Physiology"],"published-print":{"date-parts":[[2019,5,1]]},"abstract":"<jats:p> Patients suffering from heart failure with reduced ejection fraction (HFrEF) experience impaired limb blood flow during exercise, which may be due to a disease-related increase in \u03b1-adrenergic receptor vasoconstriction. Thus, in eight patients with HFrEF (63\u2009\u00b1\u20094 yr) and eight well-matched controls (63\u2009\u00b1\u20092 yr), we examined changes in leg blood flow (Doppler ultrasound) during intra-arterial infusion of phenylephrine (PE; an \u03b1<jats:sub>1<\/jats:sub>-adrenergic receptor agonist) and phentolamine (Phen; a nonspecific \u03b1-adrenergic receptor antagonist) at rest and during dynamic single-leg knee-extensor exercise (0, 5, and 10 W). At rest, the PE-induced reduction in blood flow was significantly attenuated in patients with HFrEF (\u221215\u2009\u00b1\u20097%) compared with controls (\u221236\u2009\u00b1\u20095%). During exercise, the controls exhibited a blunted reduction in blood flow induced by PE (\u221212\u2009\u00b1\u20094, \u221210\u2009\u00b1\u20094, and \u22129\u2009\u00b1\u20092% at 0, 5, and 10 W, respectively) compared with rest, while the PE-induced change in blood flow was unchanged compared with rest in the HFrEF group (\u22128\u2009\u00b1\u20095, \u221210\u2009\u00b1\u20093, and \u221214\u2009\u00b1\u20093%, respectively). Phen administration increased leg blood flow to a greater extent in the HFrEF group at rest (+178\u2009\u00b1\u200934% vs. +114\u2009\u00b1\u200928%, HFrEF vs. control) and during exercise (36\u2009\u00b1\u20096, 37\u2009\u00b1\u20097, and 39\u2009\u00b1\u20096% vs. 13\u2009\u00b1\u20093, 14\u2009\u00b1\u20091, and 8\u2009\u00b1\u20093% at 0, 5, and 10 W, respectively, in HFrEF vs. control). Together, these findings imply that a HFrEF-related increase in \u03b1-adrenergic vasoconstriction restrains exercising skeletal muscle blood flow, potentially contributing to diminished exercise capacity in this population. <\/jats:p>","DOI":"10.1152\/ajpregu.00345.2018","type":"journal-article","created":{"date-parts":[[2019,2,21]],"date-time":"2019-02-21T15:21:34Z","timestamp":1550762494000},"page":"R512-R524","source":"Crossref","is-referenced-by-count":33,"title":["\u03b1-Adrenergic receptor regulation of skeletal muscle blood flow during exercise in heart failure patients with reduced ejection fraction"],"prefix":"10.1152","volume":"316","author":[{"given":"Zachary","family":"Barrett-O\u2019Keefe","sequence":"first","affiliation":[{"name":"Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joshua F.","family":"Lee","sequence":"additional","affiliation":[{"name":"Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stephen J.","family":"Ives","sequence":"additional","affiliation":[{"name":"Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joel D.","family":"Trinity","sequence":"additional","affiliation":[{"name":"Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah"},{"name":"Department of Internal Medicine, University of Utah, Salt Lake City, Utah"},{"name":"Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Melissa A. 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