The Production of Blood Platelets in the Lungs

Abstract

The present investigation had its origin in the suggestion that the blood of the emergent vein of the organ or organs in which platelet production is taking place should show a higher platelet count than the venous blood of other organs. In order to carry out this idea it was essential to find a satisfactory method of counting both platelets and erythrocytes in samples of blood removed from the veins by means of a syringe. Such a method was devised. It is described in detail below. In applying this method to various arteries and veins it was found that the platelet count, relative to the number of erythrocytes, was, in general, higher in the arteries t h a n in the veins, indicating an increase in the n u m b e r of platelets during the passage of the blood through the lungs. This point, therefore, was made the subject of a special study b y experimental and histological methods, the results of which are given in this paper. MethodsRemoval of Samples of Blood.--For this purpose 0.1 cc. of blood was taken from an artery or vein by means of a 0.25 cc. tuberculin syringe (B-D). The syringes used were calibrated with mercury, but the graduation as given by the makers was found to be correct. In these syringes the 0.25 cc. is divided into 25 equal parts, each representing 0.01 cc. In taking a sample of blood the syringe with needle attached was filled with the diluting mixture to mark 15. The needle (No. 24) was then inserted into the vessel and blood was drawn to mark 25, giving, therefore, 0.1 cc. of blood. The contents of the syringe were emptied into 39 cc. of the diluting mixture and the syringe was filled and emptied three times with the diluting mixture, so that the final dilution of the blood was 0.1 cc. in 40 cc. of the mixture, or 1 to 400. This mixture was stirred thoroughly for 5 minutes with an electric stirrer, the wide paddies of which were coated with bakelite varnish, and samples were then taken for the counting chamber by means of an appropriate 177

Effects of Oxygen-Induced Lung Damage on Megakaryocytopoiesis and Platelet Homeostasis in a Rat Model

“…In the healthy adult animals, passage of mixed venous blood through the pulmonary capillary bed resulted in a significant reduction in MK count by 65%, which was associated with a 34% increase in platelet count. These findings were consistent with those previously reported by other investigators (21,23,24), and provided further evidence that the lung is an important site for MK fragmentation and platelet release. A similar albeit slightly lesser prepulmonary and postpulmonary gradient in MK and platelet counts was also observed in the term and preterm neonatal pups, thus confirming the role of the lung in platelet release in the newborns.…”

“…The presence of MK cells in the human lungs was described by Aschoff over 100 years ago (20). Subsequently, a number of studies have demonstrated that MK were greater in abundance and cytoplasmic volume in the central venous (prepulmonary) blood than in the arterial (postpulmonary) blood (21)(22)(23)(24)(25), providing an indirect evidence that these cells are fragmented in the lungs. Studies on patients on cardiopulmonary bypass have shown that the lungs are net removers of MK from the circulation (25).…”

Microtubule and cortical forces determine platelet size during vascular platelet production

“…Alternatively, prePLTs may become trapped in the micro-capillaries of the bone marrow, lung and/or spleen where intravascular shear forces can drive PLT production. Indeed, reports of higher PLT counts in post-pulmonary vessels suggests that the lung may be a milieu for terminal PLT formation 15 . Second, we show that twisting microtubule-based forces driving circular-prePLT to barbell-proPLT conversion are governed by two major biophysical properties: microtubule coil diameter and microtubule coil thickness.…”

Studies on the Mechanism of the Shwartzman Phenomenon

“…The platelets were clumped in large aggregates, and stained poorly with hematoxylin-eosin or eosin-methylene blue. The application of Wright's stain, by the technique of Howell and Donahue (21), resulted in adequate differentiation and readily permitted the identification of these elements. No evidence of necrosis of the vessel wall could be seen at this stage, and the leucocytes both inside and outside of the capillaries and veins appeared intact.…”