MOLECULAR AND CELLULAR BIOLOGY OF CARDIAC INTERSTITIUM

肌肉纤维的缩短和力的产生被转换到体积中 以及由几何形状所要求的心室压力泵功能 肌细胞的组织和它们的机械耦合。这种耦合 是通过高度组织化的间质蛋白系统完成的。 众所周知，这种细胞外基质经历了适应性的变化 对心室负荷变化的反应，但其机制 人们对这种增长知之甚少。这项提议把一群人聚集在一起 生理学家、生物化学家和分子生物学家共同探讨 细胞外蛋白在左心室肥厚中的作用。中的研究 这一建议旨在探索基因的表达、成熟和 细胞外基质适应性生长的功能后果 在急性和渐进性起病的压力超负荷肥厚模型中。四 具体的问题将会得到解答。1)纤维连接蛋白和胶原蛋白是如何 急性压力超负荷后基因表达的变化？北方 印迹和s1核酸酶保护试验将被用来测量mrna水平。 在大鼠模型上进行急性主动脉缩窄。原位杂交将 用于确定这些mRNAs的细胞来源。的水平 转录将通过核径流分析进行评估。最后，Net 在灌流的离体心中将观察蛋白质的合成。 放射性标记的氨基酸。2)为了识别特定的机械 压力过载的后果可能会刺激儿童的成长 细胞外基质，我们将确定心肌中哪些变化 有限变形或估计的壁应力与以下变化相关 纤维连接蛋白和胶原蛋白的mRNA水平。对于这些实验，我们将 应用上述方法和三维技术 我们实验室对一只大型动物(猪)进行的应变分析 模特。3)我们将研究如何在数量、浓度和 胶原的交联度改变了残余应变，舒张期 压力-应变关系，以及收缩纤维和交叉纤维 心肌的应变。4)最后，我们将研究基因是如何 渐进式压力超载的表现及其功能后果 与急性负荷施加不同的是，在脱机时使用主动脉环扎法 猪。这些研究的结果将增加我们对 肥厚时影响心功能的因素。

Muscle fiber shortening and force generation are transduced into the volume and pressure pump function required of the ventricle by the geometric organization of the myocytes and their mechanical coupling. This coupling is accomplished through a highly organized system of interstitial proteins. It is known that this extracellular matrix undergoes adaptive changes in response to alterations in the load on the ventricle, but the mechanisms of this growth are poorly understood. This proposal brings together a group of physiologists, biochemists and molecular biologists to address the role of extracellular proteins in left ventricular hypertrophy. The studies in this proposal are designed to explore the gene expression, maturation, and functional consequences of the adaptive growth of the extracellular matrix in models of acute and gradual onset pressure overload hypertrophy. Four specific questions will be addressed. 1) How do fibronectin and collagen gene expression change in response to acute pressure overload? Northern blot and S1 nuclease protection assays will be used to measure mRNA levels following acute aortic banding in a rat model. In situ hybridization will be utilized to determine the cellular source of these mRNAs. The level of transcription will be evaluated with nuclear runoff assays. Finally, net protein synthesis will be surveyed in isolated hearts perfused with radiolabeled amino acids. 2) In order to identify specific mechanical consequences of pressure overload that may function as stimuli to growth of the extracellular matrix, we will determine which alterations in myocardial finite deformation or estimated wall stress correlate with the changes in mRNA levels for fibronectin and collagen. For these experiments we will apply both methods described above and the techniques of three dimensional strain analysis developed in our laboratory in an a large animal (pig) model. 3) We will examine how changes in the amount, concentration, and extent of crosslinking of collagen alter the residual strain, the diastolic pressure-strain relationship, and the systolic fiber and cross-fiber strains of the myocardium. 4) Finally, we will examine how the gene expression and functional consequences of gradual onset pressure overload differ from those of acute load imposition, using aortic banding in weaning pigs. The results of these studies will increase our understanding of the factors altering cardiac performance in hypertrophy.