Mechanosensation and the basis of myogenic tone development

在动态条件下，动脉张力受到多种刺激的调节，包括神经元活动、组织代谢和血管内压力。一个世纪前，贝利斯首次推测动脉可以对血压的变化做出反应。“肌源性反应”可在多种血管床中观察到，并依赖于平滑肌[Ca2+]的增加。高血压通过增加平滑肌[Ca2+]: 1)通过动脉去极化驱动的Ca2+通道活性机制；2)肌浆网（SR）内部Ca2+释放。虽然过去的研究已经澄清了哪些离子通道和储存参与其中，但问题仍然是平滑肌细胞如何实际“感知”血管内压力以促进细胞质[Ca2+]的上升。为了与这个关键问题保持一致，NSERC的提案将解决粘附复合物蛋白及其下游信号通路是否使平滑肌细胞感知机械力并提高细胞质[Ca2+]。在未来5年，申请人将研究以下机构的作用：

Under dynamic conditions, arterial tone is regulated by multiple stimuli including neuronal activity, tissue metabolism and intravascular pressure. A century ago, Bayliss first surmised that arteries could respond to changes in blood pressure. The "myogenic response" is observable in a variety of vascular beds and is dependent upon a rise in smooth muscle [Ca2+]. Elevated pressure augments smooth muscle [Ca2+] by augmenting: 1) Ca2+ channel activity through a mechanism driven by arterial depolarization; and 2) internal Ca2+ release from the sarcoplasmic reticulum (SR). While past studies have clarified which ion channels and stores participate, questions remains as to how smooth muscle cells actually "sense" intravascular pressure to facilitate the cytosolic [Ca2+] rise. In keeping with this key question, this NSERC proposal will address whether adhesion complex proteins and their downstream signaling pathways enable smooth muscle cells to sense mechanical forces and elevate cytosolic [Ca2+]. Over the next 5 years, the applicant will examine the role of: 1. Integrin receptors on cytosolic Ca2+ dynamics and myogenic tone; and 2. Focal adhesion kinase (FAK), Src tyrosine kinases and phospholipase C gamma (PLCy1) on Ca2+ dynamics and myogenic tone. Our experimental approach will synergistically employ: 1) vessel myography to assess vessel function; 2) western analysis to determine the phosphorylation state of signaling proteins; 3) confocal microscopy to measure Ca2+ dynamics; and 4) patch clamp electrophysiology to monitor ion channel activity. Integrin receptors and downstream signaling proteins will be actively manipulated using established pharmacological tools or a siRNA approach. Our focus on pressure-sensing and adhesion complex proteins will foster a deeper mechanistic appreciation of the myogenic response and its biological significance to cardiovascular function.