COX/iNOS dependence for angiotensin-II-induced endothelial dysfunction

Area of Science:

• Cardiovascular Biology
• Molecular Pharmacology
• Vascular Physiology

Background:

• Vascular dysfunction, induced by angiotensin-II, arises from direct cellular effects and indirect hemodynamic changes.
• Understanding the roles of cyclooxygenase (COX) and inducible nitric oxide synthase (iNOS) in angiotensin-II-mediated vascular effects is crucial.

Purpose of the Study:

• To investigate the impact of angiotensin-II on COX and iNOS expression and activity in cultured aortas.
• To elucidate the contribution of COX and iNOS to angiotensin-II-induced vascular reactivity changes and endothelial dysfunction.

Main Methods:

• Isolated mouse aortic rings were cultured with angiotensin-II to induce vascular dysfunction.
• Vascular reactivity was assessed in a bath chamber; COX-1/COX-2 expression via immunofluorescence.
• Nitric oxide (NO) production, oxidative stress, and nitrosative stress were quantified using biochemical and fluorescent methods.

Main Results:

• Angiotensin-II impaired endothelium-dependent relaxation, an effect reversed by AT1 receptor blockade and COX/iNOS inhibition.
• Increased COX-2 expression and release of vasoconstrictor prostanoids were observed, alongside elevated reactive oxygen species and NO production.
• iNOS inhibition mitigated NO enhancement and nitrotyrosine accumulation, indicating its role in nitrosative stress.

Conclusions:

• Angiotensin-II induces vascular inflammation and endothelial dysfunction through a pathway codependently involving iNOS and COX.
• The findings identify TP and EP receptors as key mediators in this angiotensin-II-triggered vascular response.
• Targeting iNOS and COX pathways may offer therapeutic strategies for angiotensin-II-related vascular complications.