title: Response of pulmonary (circulating) megakaryocytes to experimentally induced consumption coagulopathy in rabbits.
abstract: The effects of slow temporary infusion of a tissue thromboplastin solution into the superior vena cava on pulmonary as well as circulating megakaryocytes were studied in 40 rabbits (2-48 hours after infusion) and related to 6 noninfused and 7 infused with normal saline. This is a simple and specific method of inducing a fall in blood platelet levels and thereby an activation of thrombocytopoiesis and megakaryocytopoiesis. The induced intravascular coagulation is probably counterbalanced by an activated fibrinolysis allowing the animals to survive the infusion and thereby offering the possibility of studying the long-term effects. An increase to about  300% of the normal values in circulating as well as pulmonary megakaryocytes was found 20 and 24 hours after the onset of the infusions respectively. The number of circulating and pulmonary megakaryocytes, showing great individual variations, however, dropped to normal levels within 28 hours after onset of the infusions, which means that megakaryocytes remain detectable for less than eight hours in the lungs. No increase was found in pulmonary megakaryocytes in the control (saline infused) group. In our opinion the entrance of megakaryocytes from the bone marrow into the blood circulation in an incidental event, the number in the circulation reflecting the activity of megakarycocytopoiesis. This experiment supports our suggestion that intravascular coagulation is one of the major pathophysiological mechanisms leading to an increase in pulmonary megakaryocytes.
mesh_terms: D000818:Animals; D001772:Blood Cell Count; D001792:Blood Platelets / Q000187:drug effects; D004211:Disseminated Intravascular Coagulation / Q000097:blood* / Q000139:chemically induced; D005340:Fibrinogen / Q000032:analysis; D007263:Infusions, Parenteral; D008168:Lung / Q000098:blood supply*; D008297:Male; D008533:Megakaryocytes / Q000187:drug effects; D011655:Pulmonary Embolism / Q000209:etiology; D011817:Rabbits; D012965:Sodium Chloride / Q000008:administration & dosage / Q000494:pharmacology; D013925:Thromboplastin / Q000008:administration & dosage
chemical_list: D012965:Sodium Chloride; D005340:Fibrinogen; D013925:Thromboplastin