[The pulmonary hemodynamics changes following experimental myocardial ischemia in rabbits with decreased arterial...

In acute experiments in rabbits the changes of the pulmonary hemodynamics following myocardial ischemia in the region of the descendent left coronary artery were studied in normotensive animals and after the infusion of histamine or isoproterenol. Following histamine intravenous in fusion the pulmonary artery pressure and pulmonary vascular resistance were increased, however the pulmonary artery flow decreased. In these conditions myocardial ischemia caused the returning of the elevated pulmonary artery pressure to normal level following the diminishing of the pulmonary artery flow to the same level as in normotensive rabbits. Meanwhile the pulmonary vascular resistance remained elevated. Following isoproterenol intravenous injection the isoproterenol artery pressured and flow, pulmonary vascular resistance were decreased. In these conditions myocardial ischemia caused the decrease of the isoproterenol artert pressure, more, than in normotensive rabbits, which was the result of diminishing left atrial pressure, however, the pulmonary artery flow and pulmonary vascular resistance decreased in both cases to the same level. Thus we concluded, that following myocardial ischemia in rabbits with decreased arterial pressure, the changes of pulmonary artery pressure depend on pulmonary artery flow and left atrial pressure changes. The shifts of the pulmonary artery flow depend on venous return ones and does not correlated with pulmonary vascular resistance changes.