Is active skeletal muscle functionally vasoconstricted during dynamic exercise in conscious dogs?
Is active skeletal muscle functionally vasoconstricted during dynamic exercise in conscious dogs?
复制标题
在有意识的狗进行动态运动时，活跃的骨骼肌是否会出现功能性血管收缩？
DOI：
10.1152/ajpregu.1997.272.1.r386
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Butler,JL
中科院分区：
文献类型：
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作者：
O'Leary,DS;Robinson,ED;Butler,JL
我们研究了在清醒的狗在分级动态运动过程中后肢血流量和血管电导的增加是否在功能上受到交感神经系统的抑制。狗长期仪器监测终端主动脉血流量（TAQ）作为后肢骨骼肌血流量和平均动脉压（MAP）的指标。功能性交感神经紧张的程度通过测量TAQ和终末主动脉血管传导性的增加来评估（TAC，计算为TAQ/MAP）对动脉内输注α-肾上腺素能拮抗剂哌唑嗪的反应（PZ; 50微克/公斤），进入后肢在休息和稳态动态（跑步机）运动范围从轻度（3.2 km/h，0%等级）到中度重负荷（8 km/h，15%等级）。该剂量的PZ完全消除了对苯肾上腺素的大后肢血管收缩反应（1微克/千克ia）。静息时，PZ使TAQ增加0.10 +/- 0.02 l/min，TAC增加1.85 +/- 0.53 ml.min-1.mmHg-1。在运动过程中，随着负荷的增加和TAQ和TAC的控制水平逐渐升高，Δ TAQ和Δ TAC与PZ输注也增加。在最高负荷下，PZ使TAQ增加0.41 +/- 0.07 l/min，TAC增加4.81 +/- 0.38 ml.min-1.mmHg-1。TAQ和TAC与PZ的增加与TAQ的控制水平线性相关，表明随着工作量的逐渐增加，交感神经系统对肌肉血管舒张的抑制作用逐渐增强。我们的结论是，在清醒的狗的动态运动过程中，交感神经系统逐步抑制正常的血管舒张活动的骨骼肌，从而限制骨骼肌灌注。
We investigated whether the increase in hindlimb blood flow and vascular conductance in conscious dogs during graded dynamic exercise is functionally restrained by the sympathetic nervous system. Dogs were chronically instrumented to monitor terminal aortic blood flow (TAQ) as an index of hindlimb skeletal muscle blood flow and mean arterial pressure (MAP). The extent of functional sympathetic tone was assessed by measuring the increase in TAQ and terminal aortic vascular conductance (TAC, calculated as TAQ/MAP) in response to intra-arterial infusion of the alpha-adrenergic antagonist prazosin (PZ; 50 micrograms/kg) into the hind-limbs at rest and during steady-state dynamic (treadmill) exercise ranging from mild (3.2 km/h, 0% grade to moderately heavy (8 km/h, 15% grade) workloads. This dose of PZ completely abolished the large hindlimb vasoconstrictor response to phenylephrine (1 microgram/kg ia). At rest, PZ increased TAQ by 0.10 +/- 0.02 l/min and TAC by 1.85 +/- 0.53 ml.min-1.mmHg-1. During exercise, as workload increased and the control levels of TAQ and TAC rose progressively delta TAQ and delta TAC with PZ infusion also increased. At the highest workload, PZ increased TAQ by 0.41 +/- 0.07 l/min and TAC by 4.81 +/- 0.38 ml.min-1.mmHg-1. The increase in TAQ and TAC with PZ were linearly related to the control level of TAQ, indicating that as workload increases progressively greater restraint of muscle vasodilation by the sympathetic nervous system occurs. We conclude that during dynamic exercise in conscious dogs the sympathetic nervous system progressively restrains the normal vasodilation in active skeletal muscle, thereby limiting skeletal muscle perfusion.