Drummond Heather A
Department of Physiology and Biophysics, University of Mississippi Medical Center Jackson, MS, USA.
Front Physiol. 2012 Aug 28;3:341. doi: 10.3389/fphys.2012.00341. eCollection 2012.
Pressure-induced constriction (also known as the "myogenic response") is an important mechano-dependent response in certain blood vessels. The response is mediated by vascular smooth muscle cells (VSMCs) and characterized by a pressure-induced vasoconstriction in small arteries and arterioles in the cerebral, mesenteric, cardiac, and renal beds. The myogenic response has two important roles; it is a mechanism of blood flow autoregulation and provides protection against systemic blood pressure-induced damage to delicate microvessels. However, the molecular mechanism(s) underlying initiation of myogenic response is unclear. Degenerin proteins have a strong evolutionary link to mechanotransduction in the nematode. Our laboratory has addressed the hypothesis that these proteins may also act as mechanosensors in certain mammalian tissues such as VSMCs and arterial baroreceptor neurons. This article discusses the importance of a specific degenerin protein, β Epithelial Na(+) Channel (βENaC) in pressure-induced vasoconstriction in renal vessels and arterial baroreflex function as determined in a mouse model of reduced βENaC (βENaC m/m). We propose that loss of baroreflex sensitivity (due to loss of baroreceptor βENaC) increases blood pressure variability, increasing the likelihood and magnitude of upward swings in systemic pressure. Furthermore, loss of the myogenic constrictor response (due to loss of VSMC βENaC) will permit those pressure swings to be transmitted to the microvasculature in βENaC m/m mice, thus increasing the susceptibility to renal injury and hypertension.
压力诱导性收缩(也称为“肌源性反应”)是某些血管中一种重要的机械依赖性反应。该反应由血管平滑肌细胞(VSMC)介导,其特征是在脑、肠系膜、心脏和肾脏床的小动脉和微动脉中出现压力诱导性血管收缩。肌源性反应有两个重要作用;它是一种血流自动调节机制,可保护脆弱的微血管免受全身血压引起的损伤。然而,肌源性反应起始的分子机制尚不清楚。退化蛋白与线虫的机械转导有很强的进化联系。我们实验室探讨了这样一种假说,即这些蛋白在某些哺乳动物组织(如VSMC和动脉压力感受器神经元)中也可能作为机械传感器发挥作用。本文讨论了一种特定的退化蛋白,即β上皮钠通道(βENaC)在肾血管压力诱导性血管收缩和动脉压力反射功能中的重要性,这是在βENaC减少的小鼠模型(βENaC m/m)中确定的。我们提出,压力反射敏感性的丧失(由于压力感受器βENaC的丧失)会增加血压变异性,增加全身压力向上波动的可能性和幅度。此外,肌源性收缩反应的丧失(由于VSMC βENaC的丧失)将使这些压力波动传递到βENaC m/m小鼠的微血管,从而增加肾损伤和高血压的易感性。