LIMITATION TO EXERCISE AFTER PNEUMONECTOMY

在成年犬肺切除术(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导致的肺泡伸展。我们发现，通过根据正常右肺形状定制的充气硅胶假体来防止右PNX术后肺扩张并不能完全阻止再生肺泡的生长，这表明其他刺激，如通过剩余肺的血流量增加，也是重要的。我们的目标是表征肺扩张和非扩张相关信号在PNX后对完全成熟犬再生肺生长的结构、细胞和生理反应的时间进程和幅度，当这些信号与急性手术创伤、应激和组织修复暂时隔离时。使用充气假体2~6个月可防止右侧PNX术后肺扩张。然后，假体被放气，允许肺扩张。在不同的动物组中，将通过重复呼吸法和高分辨率CT扫描来连续评估放气前后的生理补偿。生理测量包括压力-容量关系、最大吸氧量、肺弥散量(DLCO)及其组成成分膜弥散量(DMco)和毛细血管血容量(VC)，以及运动时DLCO、DMco和VC与肺血流量的关系。在2点到10点。术后取肺组织进行形态计量学分析，免疫组织化学、免疫金标记法、免疫印迹法、免疫沉淀法和RNA印迹法研究表皮生长因子(EGF)及其受体(EGFR)的定位和表达。选择的时间点将允许比较对肺扩张的短期或长期生长反应，而不会受到手术创伤和炎症的混杂影响，并确定PNX后早期或延迟应用机械肺泡拉伸对生长和补偿的不同影响。还将确定生理补偿、生长因子表达和结构生长之间的相关性。这项建议解决了与调节完全成熟动物的肺生长的机制和信号有关的基本问题。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。研究结果对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，即探索能够促进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.