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Pressure-induced leukocyte margination in lung postcapillary venules
Hideo Ichimura1, Kaushik Parthasarathi, Andrew C Issekutz
1lung Biology Laboratory, Department of Physiology and Cellular Biophysics, Columbia University, New York, New York, USA.
Summary
Lung pressure elevation causes leukocyte margination by decreasing plasma velocity, with P-selectin playing a critical role. This study reveals plasma flow dynamics as the key determinant in this process.
Area of Science:
- Pulmonary Physiology
- Immunology
- Microcirculation Research
Background:
- Elevated pressure in lung venules increases P-selectin, but its role in leukocyte margination is debated.
- Understanding leukocyte behavior in pulmonary microcirculation is crucial for inflammatory lung diseases.
Purpose of the Study:
- To investigate the role of P-selectin in pressure-induced leukocyte margination in rat lung postcapillary venules.
- To determine the relationship between plasma velocity and leukocyte margination under elevated pressure.
Main Methods:
- Real-time fluorescence imaging of leukocyte margination in isolated blood-perfused rat lungs.
- Quantification of rhodamine 6G-labeled leukocytes and fluorescent microbeads to assess margination and plasma velocity.
- Inhibition studies using P-selectin blocking antibodies and fucoidin.
Main Results:
- Pressure elevation significantly increased leukocyte margination, confirmed by fluorescence imaging.
- P-selectin blockade and fucoidin treatment reduced pressure-induced leukocyte margination.
- Decreased plasma velocity, observed during pressure elevation and experimentally induced, prolonged leukocyte margination.
Conclusions:
- P-selectin is critical for initiating pressure-induced leukocyte margination in lung postcapillary venules.
- Reduced plasma velocity is the primary determinant of leukocyte margination during elevated lung pressure.
- Findings elucidate mechanisms relevant to inflammatory lung conditions and microvascular responses.