Do incremental increases in blood pressure elicit neointimal plaques through endothelial injury?

Area of Science:

• Cardiovascular physiology
• Atherosclerosis research
• Animal models in cardiovascular disease

Background:

• Maturation in fowl, particularly males, is associated with increased blood pressure (BP) and the development of neointimal plaques (NPs) in the abdominal aorta (AbA).
• These NPs share characteristics with those induced by balloon catheter injury, suggesting a potential link to endothelial injury and hemodynamic factors.

Purpose of the Study:

• To investigate if rapid increases in BP in male chicks trigger NP formation.
• To explore the potential role of endothelial injury in hemodynamically selective areas.
• To examine the effects of arginine supplementation and propranolol on BP and NP development.

Main Methods:

• 6-week-old male chicks were treated for 4 weeks with a solvent (Sv), arginine supplement (Arg), or propranolol (Prop).
• Blood pressure was monitored, and abdominal aorta samples were analyzed for neointimal plaque area and medial thickness.
• Intravascular transducers were used to measure pulse pressure changes.

Main Results:

• Both arginine and propranolol treatments prevented the maturation-dependent rise in blood pressure and significantly reduced neointimal plaque area and abdominal aorta medial thickness compared to controls.
• In older cockerels, propranolol decreased established high BP but did not reduce plaque area or medial thickness, while arginine increased both.
• Pulse pressure increased down the aorta, indicating hemodynamic influences.

Conclusions:

• Maturation-dependent increases in BP in chicks may initiate neointimal plaque formation in the lower abdominal aorta.
• Inhibition of BP increase or enhanced nitric oxide availability (via arginine) can prevent plaque formation.
• Reducing BP after it has plateaued may not reverse existing plaque development or thickness.