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Leukocyte cytoskeletal structure determines capillary plugging and network resistance
1Department of Biomedical Engineering, University of Virginia, Charlottesville 22908.
The American Journal of Physiology
|November 1, 1993
Summary
Leukocyte plugging in capillaries significantly impacts blood flow resistance. This study reveals that cytoplasmic viscosity, not cell adhesion, is the primary factor, highlighting the role of F-actin in leukocyte function.
Area of Science:
- Physiology
- Biophysics
- Microcirculation
Background:
- Leukocyte plugging in capillaries affects microvascular hemodynamics, especially during leukocyte activation.
- Previous research quantified plugging effects but lacked focus on intracellular mechanisms.
Purpose of the Study:
- To investigate the intracellular mechanisms of leukocyte plugging in capillaries.
- To determine the impact of cytoskeletal F-actin depolymerization on leukocyte plugging and microvascular resistance.
Main Methods:
- Measured leukocyte-capillary plugging frequency and duration in rat spinotrapezius muscle.
- Activated leukocytes using N-formyl-methionyl-leucyl-phenylalanine (FMLP) and cytochalasin D (CD) to depolymerize F-actin.
- Estimated microvascular flow resistance changes.
Main Results:
- Microvascular resistance increase was 1.1% in controls and 0.7% in FMLP-CD treated rats, with no significant difference.
- Cytochalasin D abolished the previously observed 16% resistance increase from FMLP activation.
- Leukocyte plugging appears primarily determined by cytoplasmic viscosity, not cell adhesion.
Conclusions:
- Leukocyte plugging in capillaries is mainly governed by leukocyte cytoplasmic viscosity.
- F-actin-mediated cytoskeletal reorganization significantly influences microvascular resistance during leukocyte activation.
- Cell adhesion plays a minimal role in capillary plugging compared to cytoplasmic viscosity.