Bradykinin causes a prolonged increase in skin microvascular permeability

Area of Science:

• Physiology
• Pharmacology
• Inflammation Research

Background:

• Bradykinin is an endogenous inflammatory mediator.
• Its precise mechanism of action, particularly regarding microvascular permeability, remains incompletely understood.
• There is ongoing debate about whether bradykinin induces a transient or sustained increase in microvascular permeability.

Purpose of the Study:

• To investigate the duration and nature of microvascular permeability changes induced by bradykinin.
• To determine if bradykinin causes a sustained increase in protein-rich lymph flow and protein flux.

Main Methods:

• Anesthetized dogs underwent intraarterial infusion of bradykinin at varying doses (0.14 to 0.54 micrograms/kg/min).
• Hindpaw lymph flow and lymph protein concentration were measured over extended periods (up to 4 hours).
• Venous hypertension was induced to further assess lymph flow dynamics.

Main Results:

• Bradykinin infusion immediately increased protein-rich hindpaw lymph flow.
• After 210 minutes, lymph flow was threefold greater than baseline, with doubled lymph protein concentration.
• Bradykinin induced a dose-related, sustained increase in lymph protein flux, persisting even after 4 hours and venous hypertension.

Conclusions:

• Bradykinin induces a sustained increase in microvascular permeability.
• This sustained effect suggests a distinct mechanism of action compared to the initial permeability increase.
• The findings clarify bradykinin's role in prolonged inflammatory responses and vascular leakage.