Increased pulmonary vascular permeability after bone marrow injection in sheep.

We determined the effects of injection of bone marrow into the pulmonary circulation on pulmonary fluid and protein exchange in sheep. We also assessed the roles of free fatty acid toxicity and secondary thrombosis as mediators of the changes in pulmonary fluid balance. Injection of small amounts of bone marrow (range 0.07 to 0.41 ml/kg) resulted in pulmonary edema associated with increases in steady-state pulmonary lymph flow and protein clearance that the characteristic of increased endothelial permeability. There was no change in plasma concentrations of free fatty acids after injection. The small increases in lymph fatty acid clearance paralleled the increases in lymph protein clearance, reflecting the rapid binding of fatty acids to albumin. Decreased plasma fibrinogen with a concomitant increase in fibrin degradation products followed the bone marrow injection, indicating the activation of intravascular coagulation. In addition, the leukocyte count rapidly decreased just after the bone marrow injection. These findings suggest that the increased permeability was due to intravascular coagulation and resultant fibrin entrapment and leukostasis, and was not a result of increased circulating fatty acids.