PHOSPHOLAMBAN MODULATION OF SMOOTH MUSCLE CONTRACTILITY

磷蛋白(PLB)是一种抑制肌质网钙-ATPase的蛋白。 在体外，PLB的磷酸化可以解除这种抑制，而且有 大量证据表明，PLB在体内调节心脏的收缩能力。 有一些证据表明，原球蛋白在平滑肌肉中也有类似的作用。 最近，Evangelia Kranias博士制造了一种pLB的“击倒”(pLB-) 老鼠。调查人员提议用这只老鼠作为研究的模型 原球蛋白在体内平滑肌中的作用。初步数据为 支持PLB是一个重要的调节器的假说 细胞内钙离子和平滑肌的重要决定因素 伸缩性。这个项目有三个具体目标。第一个目标是， 研究人员建议量化和比较Smooth的收缩能力 从PLB小鼠到年龄匹配的野生型小鼠的肌肉。这个 最初的研究将集中在强直性主动脉和门静脉相性。 有代表性的血管制剂和纵向回肠及 代表肠道和呼吸道通畅的气管制剂 肌肉。这些研究也将扩展到阻力动脉。这个 原球蛋白在基础收缩功能中的作用及其在 CAMP或CGMP途径介导的松弛将被确定。在……里面 为了达到这个目的，调查员还将核实野生环境中是否存在PLB 对肌肉进行分类，并确定这种蛋白质和钙离子的水平- ATPase。第二个目标将检验这样一种假设，即 原球蛋白-平滑肌的收缩能力是由于钙离子处理的变化 可归因于SR功能改变。这些测试将包括荧光 (Ca~(2+))i的测定及肌浆网钙离子特异性抑制剂的应用 释放和钙摄取。此目标的一个目标是确定 并调查潜在机制的性质，这些机制可能 弥补公共小巴的缺失。第三个目标是确定 无原球蛋白对体内钙泵速率的影响 定量测定正常人泵原球蛋白抑制的基线水平 组织。

Phospholamban (PLB) is a protein which inhibits the SR Ca2+-ATPase. Phosphorylation of PLB relives this inhibition in vitro and there is substantial evidence that PLB modulates cardiac contractility in vivo. There is some evidence for a similar role for PLB in smooth muscle. Recently, Dr. Evangelia Kranias has produced a PLB "knockout" (PLB-) mouse. The investigator proposes to use this mouse as a model to study the role of PLB in smooth muscle in vivo. Preliminary data are presented to support the hypothesis that PLB is an important modulator of intercellular Ca2+ and a significant determinant of smooth muscle contractility. This project has three specific aims. In the first aim, the investigator proposes to quantitate and compare contractility in smooth muscle from the PLB- mouse to that in age-matched wild type mice. The initial studies will focus on the tonic aorta and the phasic portal vein as representative vascular preparations and the longitudinal ileum and trachea preparations, representative of enteric and airway smooth muscle. These studies will also be extended to resistance arteries. The role of PLB in baseline contractile functions, as well as its importance in relaxation mediated by CAMP or CGMP pathways will be determined. In this Aim the investigator will also verify the presence of PLB in wild type muscles and establish the levels of this protein and of the Ca2+- ATPase. The second Aim will test the hypothesis that alterations in contractility in PLB-smooth muscles are due to changes in Ca2+ handling attributable to altered SR function. These tests will include fluorescent measurements of (Ca2+)I and the use of specific inhibitors of SR Ca2+ release and Ca2+ uptake. A goal of this aim is to determine the magnitude and investigate the nature of potential mechanisms that may compensate for the absence of PLB. The third aim is to determine the effects of the absence of PLB on the Ca2+ pump rate in vivo, and to quantify the baseline level of PLB inhibition of the pump in normal tissue.