EETs promote hypoxic pulmonary vasoconstriction via constrictor prostanoids.

Area of Science:

• Cardiovascular Physiology
• Pulmonary Hypertension Research
• Molecular Pharmacology

Background:

• Epoxyeicosatrienoic acids (EETs) are bioactive lipids involved in vascular regulation.
• Soluble epoxide hydrolase (sEH) metabolizes EETs, influencing their availability and biological effects.
• Hypoxia triggers pulmonary vasoconstriction, a key factor in high-altitude adaptation and pulmonary hypertension.

Purpose of the Study:

• To investigate the role of EETs in mediating pulmonary vascular responses to hypoxia.
• To determine how inhibiting sEH affects hypoxia-induced pulmonary vasoconstriction (HPV).
• To elucidate the downstream signaling pathways, including prostaglandin metabolism, involved in EET-mediated HPV.

Main Methods:

• Utilized wild-type (WT) and sEH knockout (sEH-KO) mice, and WT mice treated with an sEH inhibitor (t-TUCB).
• Measured right ventricular systolic pressure (RVSP) under normoxic and hypoxic conditions.
• Assessed isometric tension in isolated pulmonary arteries and quantified HPV, with and without EET antagonists, exogenous EETs, and inhibitors of cyclooxygenase (COX) and thromboxane pathways.

Main Results:

• Hypoxia increased RVSP, with a greater effect in sEH-KO and t-TUCB-treated mice, indicating an EET-mediated response.
• 11,12-EET administration enhanced hypoxia-induced RVSP elevation and HPV in WT pulmonary arteries.
• Enhanced HPV in sEH-deficient mice was linked to altered prostaglandin metabolism, favoring vasoconstrictors PGH2 and TXA2.

Conclusions:

• EETs play a significant role in potentiating pulmonary vascular responses to hypoxia.
• sEH deficiency or inhibition amplifies HPV through an EET-dependent mechanism involving altered prostaglandin synthesis.
• Targeting the EET pathway and its interaction with prostaglandin metabolism may offer therapeutic strategies for hypoxic pulmonary vascular diseases.