Chronic hypoxic pulmonary hypertension in rats and increased elastolytic activity

Area of Science:

• Pulmonary Medicine
• Vascular Biology
• Biochemistry

Background:

• Pulmonary hypertension (PH) involves increased pulmonary arterial pressure and vascular remodeling.
• Serine elastase inhibitors have shown potential in mitigating monocrotaline-induced PH.
• The role of elastolytic activity in hypoxia-induced PH requires further investigation.

Purpose of the Study:

• To determine if inhibiting elastolytic activity with SC-39026 can prevent vascular changes in chronic hypobaric hypoxia-induced PH.
• To assess the impact of SC-39026 on pulmonary arterial pressure and vascular muscularization.
• To investigate the underlying mechanisms, including elastin degradation and extracellular matrix alterations.

Main Methods:

• Rats were exposed to chronic hypobaric hypoxia and treated with SC-39026, a serine elastase inhibitor.
• Elastolytic activity was measured in central pulmonary arteries using a [3H]elastin substrate.
• Desmosine excretion and ultrastructural changes in elastin, collagen, fibronectin, and laminin were assessed.

Main Results:

• SC-39026 treatment reduced muscularized arteries and pulmonary arterial pressure during hypoxia.
• Hypoxia significantly increased elastolytic activity in central pulmonary arteries by day 2, an effect inhibited by SC-39026.
• No significant changes in desmosines or most glycoproteins were observed in peripheral arteries, except for decreased laminin, which was not affected by SC-39026.

Conclusions:

• Inhibition of elastolytic activity by SC-39026 ameliorates hypoxia-induced pulmonary hypertension and vascular remodeling.
• Increased elastolytic activity in pulmonary arteries is an early event in hypoxia-induced PH.
• Further studies using alpha 1-proteinase inhibitor confirmed the protective effects of elastase inhibition on pulmonary hypertension and vascular changes.