Ex vivo aortic stiffness in mice with different eNOS activity

Area of Science:

• Cardiovascular Physiology
• Biomedical Engineering
• Vascular Biology

Background:

• The aorta converts pulsatile flow to continuous flow, crucial for peripheral circulation.
• Endothelial nitric oxide (NO) is vital for regulating arterial stiffness and aortic biomechanics.
• Mouse models with altered NO signaling offer insights into NO's role in arterial stiffness.

Purpose of the Study:

• To characterize ex vivo biomechanical properties of aortic segments from mice with varying endothelial NO synthase (eNOS) expression.
• To investigate the impact of chronic NO signaling alterations on aortic diameter, compliance, and vascular reactivity.
• To explore compensatory mechanisms in response to long-term changes in NO bioavailability.

Main Methods:

• Ex vivo biomechanical assessment of aortic segments from eNOS knockout (eNOS-/-), wild-type (WT), and eNOS transgenic (eNOS-tg) mice.
• Measurement of isobaric aortic diameter and compliance.
• Assessment of vascular smooth muscle cell tone and contractile responses to adrenergic stimulation.

Main Results:

• eNOS-/- mice exhibited lower aortic diameter and compliance compared to WT mice.
• eNOS-tg mice showed increased aortic diameter and compliance relative to WT mice.
• These biomechanical differences persisted even after pharmacological NO restoration, indicating chronic adaptations beyond vasodilation.

Conclusions:

• Chronic alterations in eNOS expression significantly impact aortic biomechanics.
• The observed changes suggest compensatory mechanisms are activated to maintain hemodynamic stability.
• Endothelial function and NO bioavailability are critical determinants of aortic biomechanics and overall cardiovascular health.