Ross Amanda J, Gao Zhaohui, Pollock Jonathan P, Leuenberger Urs A, Sinoway Lawrence I, Muller Matthew D
Pennsylvania State University College of Medicine, Penn State Hershey Heart and Vascular Institute, Hershey, Pennsylvania.
Pennsylvania State University College of Medicine, Penn State Hershey Heart and Vascular Institute, Hershey, Pennsylvania
Am J Physiol Heart Circ Physiol. 2014 Nov 15;307(10):H1497-503. doi: 10.1152/ajpheart.00584.2014. Epub 2014 Sep 19.
Patients with coronary artery disease have attenuated coronary vasodilator responses to physiological stress, which is partially attributed to a β-adrenergic receptor (β-AR)-mediated mechanisms. Whether β-ARs contribute to impaired coronary vasodilation seen with healthy aging is unknown. The purpose of this study was to investigate the role of β-ARs in coronary exercise hyperemia in healthy humans. Six young men (26 ± 1 yr) and seven older men (67 ± 4 yr) performed isometric handgrip exercise at 30% maximal voluntary contraction for 2 min after receiving intravenous propranolol, a β-AR antagonist, and no treatment. Isoproterenol, a β-AR agonist, was infused to confirm the β-AR blockade. Blood pressure and heart rate were monitored continuously, and coronary blood flow velocity (CBV, left anterior descending artery) was measured by transthoracic Doppler echocardiography. Older men had an attenuated ΔCBV to isometric exercise (3.8 ± 1.3 vs. 9.7 ± 2.1 cm/s, P = 0.02) compared with young men. Propranolol decreased the ΔCBV at peak handgrip exercise in young men (9.7 ± 2.1 vs. 2.7 ± 0.9 cm/s, P = 0.008). However, propranolol had no effect on ΔCBV in older men (3.8 ± 1.3 vs. 4.2 ± 1.9 cm/s, P = 0.9). Older men also had attenuated coronary hyperemia to low-dose isoproterenol. These data indicate that β-AR control of coronary blood flow is impaired in healthy older men.
冠心病患者对生理应激的冠状动脉血管舒张反应减弱，这部分归因于β-肾上腺素能受体（β-AR）介导的机制。β-AR是否导致健康衰老过程中出现的冠状动脉血管舒张受损尚不清楚。本研究的目的是调查β-AR在健康人冠状动脉运动性充血中的作用。6名年轻男性（26±1岁）和7名老年男性（67±4岁）在接受β-AR拮抗剂静脉注射普萘洛尔和未接受治疗后，以最大自主收缩的30%进行等长握力运动2分钟。注入β-AR激动剂异丙肾上腺素以确认β-AR阻断。连续监测血压和心率，并通过经胸多普勒超声心动图测量冠状动脉血流速度（CBV，左前降支动脉）。与年轻男性相比，老年男性等长运动时的ΔCBV减弱（3.8±1.3 vs. 9.7±2.1 cm/s，P = 0.02）。普萘洛尔降低了年轻男性握力运动峰值时的ΔCBV（9.7±2.1 vs. 2.7±0.9 cm/s，P = 0.008）。然而，普萘洛尔对老年男性的ΔCBV没有影响（3.8±1.3 vs. 4.2±1.9 cm/s，P = 0.9）。老年男性对低剂量异丙肾上腺素的冠状动脉充血反应也减弱。这些数据表明，健康老年男性中β-AR对冠状动脉血流的控制受损。
