Adrenergic catecholamine trophic activity contributes to flow-mediated arterial remodeling

Area of Science:

• Cardiovascular Biology
• Vascular Physiology
• Adrenoceptor Signaling

Background:

• Alpha1-adrenoceptors (ARs) mediate vascular smooth muscle cell and fibroblast growth.
• Endogenous catecholamines contribute to arterial wall changes after injury.
• Alpha1B-ARs mediate injury-induced neointimal formation in mice.

Purpose of the Study:

• To investigate the role of catecholamines in flow-mediated arterial remodeling.
• To determine if alpha1-AR subtypes mediate adaptive arterial wall changes in response to altered blood flow.

Main Methods:

• Utilized a mouse model with reduced carotid artery blood flow via ligation.
• Compared arterial remodeling in wild-type, dopamine beta-hydroxylase knockout (DBH-KO), and alpha1D-AR knockout mice.
• Assessed changes in lumen area, vessel wall thickness, cell proliferation, apoptosis, and leukocyte accumulation.

Main Results:

• Reduced blood flow induced negative remodeling in the left carotid artery and positive remodeling in the right carotid artery of wild-type mice.
• DBH-KO mice showed significantly inhibited arterial remodeling in both arteries.
• Inhibition was linked to reduced cell proliferation, apoptosis, and leukocyte infiltration.
• Alpha1D-AR knockout mice exhibited minimal inhibition, suggesting alpha1B-AR involvement.

Conclusions:

• Catecholamines significantly contribute to both negative and positive flow-mediated arterial remodeling.
• Alpha1B-ARs are critical mediators of catecholamine-induced arterial wall adaptation to altered blood flow.
• These findings reveal a novel role for catecholamines in adaptive vascular remodeling without injury.