Increased pulmonary microvasuclar permeability induced by alpha-naphthylthiourea

Area of Science:

• Pulmonary physiology
• Vascular biology
• Toxicology

Background:

• Understanding lung microvascular permeability is crucial for diagnosing and treating pulmonary edema.
• Alpha-naphthylthiourea (ANTU) is a known pulmonary toxicant, but its precise effects on microvascular protein flux require detailed investigation.

Purpose of the Study:

• To quantitatively assess the impact of ANTU on lung microvascular permeability to plasma proteins.
• To evaluate changes in capillary pore size and extravascular lung water following ANTU administration.

Main Methods:

• Anesthetized open-chest dogs were used with cannulated lung lymphatics to measure lymph flow (Jv) and protein concentration.
• Experimental protocol involved baseline measurements, elevated left atrial pressure (Pla), ANTU infusion, and subsequent Pla elevation.
• Vascular permeability was assessed by calculating osmotic reflection coefficient (sigma d) and equivalent pore radii.

Main Results:

• ANTU administration resulted in an 8.6-fold increase in lymphatic total protein clearance.
• The osmotic reflection coefficient (sigma d) decreased from 0.65 to 0.40, indicating increased permeability.
• Equivalent pore radii increased, and extravascular lung water significantly rose post-ANTU.

Conclusions:

• ANTU markedly increases lung microvascular permeability to plasma proteins.
• The observed changes suggest alterations in capillary pore size and contribute to increased lung water accumulation.
• This study provides a quantitative assessment of ANTU-induced pulmonary microvascular injury.