LIMITATION TO EXERCISE AFTER PNEUMONECTOMY

成年犬全肺切除术（PNX）后诱导再生肺生长的一个主要信号被认为是由于剩余肺的扩张而引起的肺泡拉伸。我们发现，通过一个根据正常右肺形状定制的充气硅胶假体来防止右侧PNX术后肺扩张，并不能完全阻止肺泡再生生长，这表明其他刺激，如增加剩余肺的血流量，也很重要。我们的目的是表征肺扩张和非扩张相关信号在PNX后完全成熟犬肺再生生长中的结构、细胞和生理反应的时间过程和强度，当这些信号暂时与急性外科创伤、应激和组织修复分离时。右侧PNX术后肺扩张将被充气假体阻止2至6个月。然后假体放气，允许肺扩张。生理补偿将通过再呼吸法和高分辨率CT扫描在不同的动物组中进行连续评估。生理测量包括压力-容积关系、最大摄氧量、肺弥漫性（DLco）及其组分膜弥漫性（dco）和毛细血管血容量（Vc），以及运动时DLco、dco和Vc与肺血流量的关系。在假体放气后2 ~ 10mo，采集肺组织，通过形态学分析进行详细的结构分析，并通过免疫组织化学、免疫金标、免疫印迹、免疫沉淀和RNA印迹研究表皮生长因子（EGF）及其受体（EGFR）的定位和表达。选择的时间点将允许比较短期或长期肺扩张的生长反应，而不受手术创伤和炎症的混淆影响，并确定PNX术后早期或延迟应用机械肺泡拉伸对生长和代偿的不同影响。生理补偿、生长因子表达和结构生长之间的关系也将被定义。这一建议解决了关于调节完全成熟动物肺生长的机制和信号的基本问题。这是第一个系统地分离和解剖体内肺生长的主要假定刺激的模型。这些结果对于理解生长调节机制具有广泛的科学意义，并将推进我们的长期目标，即探索可以增强慢性肺病患者再生肺生长的治疗方法。

A major signal inducing regenerative lung growth in adult dogs after pneumonectomy (PNX) is thought to be alveolar stretch due to expansion of the remaining lung. We found that preventing lung expansion after right PNX by an inflated silicone prosthesis customized to the shape of the normal right lung does not completely prevent regenerative alveolar growth, suggesting that other stimuli such as increased blood flow through the remaining lung, are also important. Our objective is to characterize the time course and magnitude of structural, cellular and physiologic responses induced by lung expansion and non-expansion related signals for regenerative lung growth in fully mature dogs after PNX when these signals are temporally isolated from the acute surgical trauma, stress and tissue repair. Lung expansion after right PNX will be prevented by an inflated prosthesis for 2 to 6 mo. Then the prosthesis is deflated allowing lung expansion. Physiologic compensation will be assessed serially before and after deflation by a rebreathing method and high resolution CT scan in separate groups of animals. Physiological measurements include pressure-volume relationships, maximal o2 uptake, lung diffusing capacity (DLco) and its components membrane diffusing capacity (DMco) and capillary blood volume (Vc), as well as relationships of DLco, DMco and Vc to pulmonary blood flow during exercise. At 2 to 10 mo. after prosthesis deflation, lung tissue is harvested for detailed structural analysis by morphometry, and for studying the localization and expressions of epidermal growth factor (EGF) and its receptor (EGFR) by immunohistochemical, immunogold labeling, immunoblot, immunoprecipitation and RNA blot. Time points selected will allow comparison of short-term or long-term growth responses to lung expansion without the confounding effects of surgical trauma and inflammation, and to determine differential effects of early or delayed application of mechanical alveolar stretch after PNX on growth and compensation. Correlations between physiological compensation, growth factor expression and structural growth will also be defined. This proposal addresses fundamental issues regarding the mechanisms and signals that mediate lung growth in fully mature animals. This is the first model to systematically isolate and dissect the major putative stimuli of lung growth in vivo. Results have broad scientific importance to understanding growth-regulating mechanisms and will advance our long-range goal, which is to explore therapeutic approaches that can augment regenerative lung growth in patients with chronic lung disease.