Pulmonary haemodynamics in awake rats following treatment with endotracheal pancreatic elastase.

The purpose of this paper was to study pulmonary haemodynamics in an elastase-induced emphysema model in awake rats (Group-EL, n = 9) in comparison with saline-treated controls (Group-C, n = 12). Four weeks before haemodynamic study, porcine pancreatic elastase and normal saline were intratracheally instilled in Group-EL and Group-C, respectively. Indwelling pulmonary artery and abdominal aortic catheters were positioned two days before the haemodynamic study. Breathing room air, mean pulmonary artery pressure (Ppa) tended to be higher in Group-EL than in Group-C, although the difference was not statistically significant. Systemic pressure, total systemic vascular resistance and cardiac index did not differ between groups. When exposed to 10% O2, Ppa and pulmonary vascular resistance (PVR) of both groups rose significantly. The increase of Ppa, (but not PVR) in Group-EL during hypoxia was significantly higher than that in Group-C. The magnitude of hypoxic pulmonary vasoconstriction (HPV) tended to be larger in Group-EL than in Group-C. Right ventricles of Group-EL were more hypertrophic than those of Group-C, suggesting a period of higher pulmonary artery pressure than for Group-C. The present results imply that the pressor response of pulmonary vasculature to acute alveolar hypoxia is possibly enhanced in awake rats upon examination four weeks after elastase treatment.