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Reduced RBC versus plasma microvascular flow due to endotoxin
Circulatory Shock
|January 1, 1986
Summary
Escherichia coli endotoxin causes microvascular changes, including vasoconstriction and red blood cell aggregation. This leads to altered blood flow dynamics, with plasma moving faster than red blood cells in shock.
Area of Science:
- Physiology
- Microcirculation Research
- Endotoxic Shock Models
Background:
- Microvascular transport of red blood cells (RBCs) and plasma is complex.
- Escherichia coli endotoxin is known to cause microcirculatory disturbances.
Purpose of the Study:
- To investigate the effects of endotoxin on RBC and plasma transport in microvascular circuits.
- To understand the mechanisms behind altered hemodynamics and rheology in endotoxin shock.
Main Methods:
- Wistar male rats were infused with Escherichia coli endotoxin.
- Fluorescently labeled RBCs and dextran were used to track flow.
- Videomicroscopy and densitometry measured time-concentration curves in arterioles and venules.
Main Results:
- Endotoxin caused a decrease in aortic pressure and significant vasoconstriction (50% reduction in diameter).
- Initially, RBC velocity exceeded plasma velocity; post-endotoxin, plasma velocity surpassed reduced RBC velocity.
- Red blood cell aggregation and increased transit times for RBCs were observed, indicating restricted flow.
Conclusions:
- Endotoxin shock induces cell aggregation, vasoconstriction, and recruitment of alternate vascular circuits, impeding RBC flow.
- Plasma bypasses aggregated red blood cells, flowing more rapidly in terminal shock stages.