MAXIMUM HEART-RATE RESPONSES TO EXERCISE AND ISOPROTERENOL IN THE TRAINED RAT
MAXIMUM HEART-RATE RESPONSES TO EXERCISE AND ISOPROTERENOL IN THE TRAINED RAT
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DOI：
10.1152/ajpregu.1988.254.5.r834
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发表时间：
1988-05-01
影响因子：
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通讯作者：
ATKINSON, KJ
中科院分区：
文献类型：
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作者：
BOLTER, CP;ATKINSON, KJ
雄性大鼠被分配到轻度（C）或剧烈（T）跑步项目。两组均以 30 m/min 的速度跑步，海拔 8%。在 16 周内，T 和 C 完成了 2,939 .+-。 72 和 507 .+-。 7 分钟（平均值.+-.SE）。在分级跑步测试中，T 和 C 的最大运动心率为 542 .+-。 7 和 554 .+-。 6 次/分钟（P > 0.05）。体内和体外最大有效浓度异丙肾上腺素 (ISO) 引起的心率为 483.+-。 8 和 489 .+-。 T 为 11 次/分钟，499 .+-。 5和502.+-。 C 为 5 次/分钟（组或治疗之间没有差异）。静息状态（353 .+-. 7 vs. 373 .+-. 4 次/分钟）和体外内在状态（231 .+-. 22 与 299 .+-. 22 次/分钟）的 T 中记录的心率较低（两种情况下 P < 0.05）。最大 ISO 刺激心率和最大运动心率之间的差异归因于温度差异。在另一组经过轻度训练的大鼠中，当心率接近运动最大值时，在剧烈运动期间静脉注射 ISO。 ISO 后的心率没有增加超过对照跑步中观察到的最大心率。结论是，在剧烈运动期间可以引发对交感神经刺激的最大变时性反应，并且最大运动心率反映了这一限制，而不是心脏交感神经活动的饱和度。
Male rats were assigned to light (C) or strenuous (T) running programs. Both groups ran at 30 m/min, 8% elevation. Over 16 wk, T and C completed 2,939 .+-. 72 and 507 .+-. 7 min (mean .+-. SE). In a graded running test, maximum exercise heart rates for T and C were 542 .+-. 7 and 554 .+-. 6 beats/min (P > 0.05). Heart rates elicited by maximum effective concentrations of isoproterenol (ISO) in vivo and in vitro were 483 .+-. 8 and 489 .+-. 11 beats/min for T and 499 .+-. 5 and 502 .+-. 5 beats/min for C (no difference between groups or treatments). A lower heart rate was recorded in T for both resting (353 .+-. 7 vs. 373 .+-. 4 beats/min) and in vitro intrinsic states (231 .+-. 22 vs. 299 .+-. 22 beats/min) (P < 0.05 for both conditions). The difference between maximum ISO-stimulated and maximum exercise heart rates was attributed to a temperature difference. In a separate group of lightly trained rats, ISO was administered intravenously during hard exercise when heart rate approached exercise maximum. Heart rate after ISO did not increase beyond the maximum heart rate observed in a control run. It was concluded that the maximum chronotropic response to sympathetic stimulation can be elicited during hard exercise and that maximum exercise heart rate reflects this limit rather than a saturation of cardiac sympathetic activity.