Temperature modulates P2X receptor-mediated cardiovascular responses to muscle afferent activation
Temperature modulates P2X receptor-mediated cardiovascular responses to muscle afferent activation
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DOI：
10.1152/ajpheart.01303.2005
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发表时间：
2006-09-01
影响因子：
4.8
通讯作者：
Li, Jianhua
中科院分区：
文献类型：
--
作者：
Gao, Zhaohui;Kehoe, Valerie;Li, Jianhua
静态肌肉收缩会增加 ATP 释放到肌肉间隙中。肌肉中 ATP 升高会刺激细纤维肌肉传入，并通过嘌呤能 P2X 受体的参与而升高血压。此外，ATP 还能激活 P2X 受体并增强由刺激肌肉机械感受器引起的心血管反应。在这项研究中，我们检查了升高的肌肉温度是否会减弱以及降低的温度是否会增强 P2X 对反射性肌肉反应的影响。将α，β-亚甲基ATP（α，β-MeATP）注射到后肢肌肉的动脉血供中以刺激P2X受体，并在10只麻醉猫中注射α，β-MeATP时诱导肌肉拉伸以激活机械敏感的肌肉传入神经。股动脉注射 α,β-MeATP (1.0 mM) 使平均动脉压 (MAP) 分别增加 35 +/- 5 (35 摄氏度)、26 +/- 3 (37 摄氏度) 和 19 +/- 3 mmHg (39 摄氏度；P < 0.05 与 35 摄氏度)。肌肉拉伸（2 公斤）升高 MAP。当 α,β-MeATP (0.2 mM) 在 35 和 37 摄氏度下肌肉拉伸前 5 分钟动脉注射时，MAP 反应分别显着增强 34% 和 36%。然而，当肌肉温度达到39℃时，注射α、β-MeATP仅增强牵张诱发反应6%，且与肌肉温度为35和37℃时的反应相比，该反应显着减弱。此外，我们还研究了在肌肉自由灌注和肌肉循环被阻断的情况下，肌肉温度对α、β-MeATP增强静态肌肉收缩的心血管反应的影响。由于肌肉温度为 37 摄氏度，动脉注射 α、β-MeATP 可使收缩诱发的 MAP 反应分别显着增强 49%（自由灌注）和 53%（缺血状态）。值得注意的是，这种效应在39°C的肌肉温度下显着减弱。这些数据表明P2X受体对反射性肌肉反应的影响对肌肉温度的变化敏感，并且升高的温度会减弱该反应。
Static muscle contraction increases ATP release into the muscle interstitial space. Elevated ATP in muscle stimulates thin fiber muscle afferents and increases blood pressure via engagement of purinergic P2X receptors. In addition, ATP activates P2X receptors and enhances cardiovascular responses induced by stimulation of muscle mechanoreceptors. In this study, we examined whether elevated muscle temperature would attenuate and whether reduced temperature would potentiate P2X effects on reflex muscle responses. alpha,beta-Methylene ATP (alpha,beta-MeATP) was injected into the arterial blood supply of hindlimb muscle to stimulate P2X receptors, and muscle stretch was induced to activate mechanically sensitive muscle afferents as alpha,beta-MeATP was injected in 10 anesthetized cats. Femoral arterial injection of alpha,beta-MeATP (1.0 mM) increased mean arterial pressure (MAP) by 35 +/- 5 (35 degrees C), 26 +/- 3 (37 degrees C), and 19 +/- 3 mmHg (39 degrees C; P < 0.05 vs. 35 degrees C), respectively. Muscle stretch ( 2 kg) elevated MAP. The MAP response was significantly enhanced 34% and 36% when alpha,beta-MeATP (0.2 mM) was arterially infused 5 min before muscle stretch at 35 and 37 degrees C, respectively. However, as muscle temperature reached 39 degrees C, the stretch-evoked response was augmented only 6% by alpha, beta-MeATP injection, and the response was significantly attenuated compared with the response with muscle temperature of 35 and 37 degrees C. In addition, we also examined effects of muscle temperature on alpha, beta-MeATP enhancement of the cardiovascular responses to static muscle contraction while the muscles were freely perfused and the circulation to the muscles was occluded. Because muscle temperature was 37 degrees C, arterial injections of alpha, beta-MeATP significantly augmented contraction-evoked MAP response by 49% (freely perfused) and 53% (ischemic condition), respectively. It is noted that this effect was significantly attenuated at a muscle temperature of 39 C. These data indicate that the effect of P2X receptor on reflex muscle response is sensitive to alternations of muscle temperature and that elevated temperature attenuates the response.