Development of an isolated, pulsatile blood-perfused rat lung model for evaluating the preserved lung functions

The purpose of this study was to develop an isolated, pulsatile blood-perfused rat lung model that allows us to evaluate the preserved lung functions. Lungs isolated from Sprague-Dawley rats, were perfused with venous whole blood by either a pulsatile or constant flow. The effuent was continuously deoxygenated with a 95% N₂/5% CO₂ gas mixture. Airway resistance, lung compliance, elastic work, flow resistive work, pulmonary vascular resistance, and blood gas analysis were assessed. Pressor responses toN ^G -monomethyl-l-arginine (l-NMMA) were compared between pulsatile and constant blood flow. At a flow of 0.1 ml/g body weight/min, pulsatile perfusion allowed for stable perfusion at least for 2h (mean 162.5±15.1 min) with stable aerodynamic and hemodynamic variables including blood gas tensions, whereas constant perfusion resulted in immediate lung failure. Whenl-NMMA was added to the perfusate, the mean pulmonary artery pressure did not show any change in the constant flow (6.0±2.6% increase), but did show a significant increase in the pulsatile flow (45±11% increase). Pulsatile blood flow reduced the pulmonary vascular resistance relative to the constant flow and allowed for a 2-h perfusion period to evaluate the lung function. The vasorelaxant mechanism in the pulsatile perfusion is related in part to the endothelial-dependent relaxation observed in the nitric oxide pathway. Presented in part at the 79th, Annual Clinical Congress of the American College of Surgeons (ACS) held in San Francisco, CA USA, 1993.