Eysmann S B, Gervino E, Vatner D E, Katz S E, Decker L, Douglas P S
Charles A. Dana Research Institute and Harvard-Thorndike Laboratory, Department of Medicine, Beth Israel Hospital, Boston 02215, USA.
J Appl Physiol (1985). 1996 Feb;80(2):616-22. doi: 10.1152/jappl.1996.80.2.616.
To examine whether beta-adrenergic desensitization occurs after prolonged exercise, echocardiograms, heart rate responses to isoproterenol, plasma catecholamines, and circulating lymphocyte beta-adrenergic receptors were examined in 10 sedentary normal subjects at rest and after brief (10 min) and exhaustive (mean duration 95 min) cycle exercise. Resting end-diastolic volume and ejection fraction were significantly reduced after exercise (from 120 +/- 34 to 100 +/- 26 ml and from 60 +/- 0.4 to 54 +/- 0.6%, respectively; both P < 0.05). The amount of isoproterenol needed to increase heart rate 15 and 25 beats/min increased in a dose- (exercise duration) related fashion, and the increase in amount of isoproterenol needed after prolonged exercise was closely related to the decrease in ejection fraction (r2 = 0.67, P = 0.004). Circulating lymphocyte beta-receptor density and affinity, agonist binding, and adenylylcyclase levels were unchanged with prolonged exercise. In conclusion, prolonged exercise in sedentary normal subjects resulted in reduced cardiac chronotropic responsiveness to isoproterenol that was not reflected in peripheral lymphocyte beta-adrenergic-receptor downregulation.
为了研究长时间运动后是否会发生β-肾上腺素能脱敏，对10名久坐不动的正常受试者在静息状态下以及进行短时间（10分钟）和力竭性（平均持续时间95分钟）的自行车运动后，进行了超声心动图、对异丙肾上腺素的心率反应、血浆儿茶酚胺以及循环淋巴细胞β-肾上腺素能受体的检测。运动后静息舒张末期容积和射血分数显著降低（分别从120±34降至100±26ml，从60±0.4降至54±0.6%；P均<0.05）。使心率增加15次/分钟和25次/分钟所需的异丙肾上腺素量以剂量（运动持续时间）相关的方式增加，长时间运动后所需异丙肾上腺素量的增加与射血分数的降低密切相关（r2 = 0.67，P = 0.004）。长时间运动后循环淋巴细胞β受体密度、亲和力、激动剂结合及腺苷酸环化酶水平均未改变。总之，久坐不动的正常受试者进行长时间运动后，心脏对异丙肾上腺素的变时反应性降低，而外周淋巴细胞β-肾上腺素能受体下调并未体现这一点。
