Oxygen radicals induce pulmonary vasoconstriction in pigs without activating plasma proteolytic cascade systems

Area of Science:

• Physiology
• Biochemistry
• Pharmacology

Background:

• The oxygen radical generating system, hypoxanthine-xanthine oxidase, plays a role in various physiological and pathological processes.
• Pulmonary hemodynamics and plasma proteolytic systems are crucial for maintaining lung function and regulating vascular tone.
• Understanding the interplay between oxygen radicals and these systems is vital for developing therapeutic strategies.

Purpose of the Study:

• To investigate the effects of infusing hypoxanthine-xanthine oxidase on pulmonary hemodynamics in pigs.
• To examine the impact of this oxygen radical system on plasma kallikrein-kinin and fibrinolytic systems.
• To evaluate the potential modulatory effects of indomethacin, allopurinol, and catalase on these responses.

Main Methods:

• Pigs were infused with xanthine oxidase into the pulmonary circulation to generate oxygen radicals.
• Pulmonary hemodynamics, including vasoconstriction and vascular resistance, were monitored.
• Plasma samples were analyzed for the activation of the kallikrein-kinin and fibrinolytic systems.
• The effects of indomethacin, allopurinol, and catalase were assessed.

Main Results:

• A significant pulmonary vasoconstriction and increased vasculature resistance were observed, peaking at 25 minutes.
• These effects were notably attenuated by the administration of indomethacin, allopurinol, and catalase.
• No evidence of activation in the plasma kallikrein or fibrinolytic systems was detected during the 130-minute observation period.

Conclusions:

• The hypoxanthine-xanthine oxidase system induces pulmonary vasoconstriction in pigs.
• Indomethacin, allopurinol, and catalase can mitigate the pulmonary hemodynamic effects of this system.
• The study did not find evidence that this oxygen radical system activates plasma kallikrein or fibrinolytic pathways.