MOLECULAR AND CELLULAR BIOLOGY OF CARDIAC INTERSTITIUM

肌纤维缩短和力的产生被转换成体积 以及心室所需的压力泵功能 肌细胞的组织及其机械耦合。 这种耦合 是通过一个高度组织化的间质蛋白系统完成的。 众所周知，这种细胞外基质在生长过程中会发生适应性变化。 对心室负荷变化的反应，但 人们对这种增长知之甚少。 这一提议汇集了一群 生理学家，生物化学家和分子生物学家的作用， 细胞外蛋白在左心室肥大中的作用 中的研究 该提案旨在探索基因表达，成熟， 细胞外基质适应性生长的功能后果 急性和渐进性压力超负荷肥大模型。 四 将讨论具体问题。 1)纤维连接蛋白和胶原蛋白 急性压力超负荷时基因表达的变化？ 北方 印迹和S1核酸酶保护试验将用于测量mRNA水平 在大鼠模型中急性主动脉缩窄后。 原位杂交将 用于确定这些mRNA的细胞来源。 水平 转录将用核径流测定来评估。 最后，网 蛋白质合成将在离体心脏中进行调查， 放射性标记的氨基酸。 2)为了识别特定的机械 压力超负荷的后果，可能作为刺激增长的功能， 细胞外基质，我们将确定哪些改变，在心肌 有限变形或估计的壁应力与 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 我们实验室在大型动物（猪）中开发的菌株分析 模型 3)我们将研究如何改变的数量，浓度， 胶原的交联程度改变残余应变、舒张压、收缩压和舒张压。 压力-应变关系，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 渐进性压力超负荷的表达和功能后果 与急性负荷不同，在断奶时使用主动脉结扎 猪 这些研究的结果将增加我们对 肥大时改变心脏功能的因素。

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.