Steven Janke

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When alveoli are inflated, the stretched alveolar walls draw their capillaries into oval cross sections. This causes the disk-shaped red blood cells to be oriented near alveolar gas, thereby minimizing diffusion distance. We tested these ideas by measuring red blood cell orientation in histological slides from rapidly frozen rat lungs. High lung inflation(More)
Increases in pulmonary arterial pressure or blood flow raise peripheral white cell count by releasing sequestered leukocytes from the lung. The effects of altered hemodynamics, however, on the leukocyte sequestration site and on the distribution of leukocyte transit times through the pulmonary microcirculation are unknown. We used in vivo fluorescence(More)
One-half of the neutrophils that enter the pulmonary circulation become temporarily trapped in capillaries. The neutrophils that are impeded make complete stops between free-flowing movements. These observations, based on in vivo microscopy, suggest that pulmonary margination is caused by neutrophils being impeded at focal sites in the capillary bed. To(More)
Individual pulmonary capillaries are not steadily perfused. By using in vivo microscopy, it can readily be demonstrated that perfusion continually switches between capillary segments and between portions of the network within a single alveolar wall. These changes in capillary perfusion occur even when upstream pressure and flow are constant. Flow switching(More)
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