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Effect of complement activation with cobra venom factor on pulmonary vascular permeability
Journal of Applied Physiology (Bethesda, Md. : 1985)
|December 1, 1986
Summary
Acute complement activation via cobra venom factor (CVF) increased pulmonary vascular resistance and lymph protein clearance in sheep. This effect was driven by increased microvascular pressure, not altered lung vascular permeability to proteins.
Area of Science:
- Pulmonary Physiology
- Immunology
- Vascular Biology
Background:
- The complement system plays a crucial role in immune responses.
- Understanding complement's impact on lung microcirculation is vital for treating inflammatory lung conditions.
Purpose of the Study:
- To investigate the effects of acute complement activation on lung vascular permeability to proteins.
- To determine the role of phospholipase A2 (PLA2) in complement-induced lung vascular changes.
Main Methods:
- Awake sheep with lung lymph fistulas were infused with cobra venom factor (CVF) to activate complement.
- Studies were conducted with and without PLA2 inhibition.
- Pulmonary hemodynamics, lymph flow, and lymph-to-plasma protein ratios were measured.
Main Results:
- Complement activation transiently increased pulmonary arterial pressure and vascular resistance.
- Pulmonary lymph flow and protein clearance increased, but vascular permeability to proteins remained unchanged.
- CVF infusion led to pulmonary neutrophil sequestration.
Conclusions:
- Acute complement activation increases pulmonary vascular resistance and lymph protein clearance.
- The observed increase in protein clearance is attributed to elevated microvascular pressure, not increased vascular permeability.
- Complement activation induces pulmonary neutrophil sequestration.