Captopril improves cerebrovascular structure and function in old hypertensive rats.

Area of Science:

• Cardiovascular Physiology
• Pharmacology
• Cerebrovascular Medicine

Background:

• Hypertension is associated with structural changes in cerebral arterioles, impacting blood flow regulation.
• Angiotensin-converting enzyme inhibitors (ACEIs) are used to manage hypertension, but their specific effects on cerebral arterioles require further investigation.

Purpose of the Study:

• To investigate the impact of captopril, an ACEI, on cerebral arterioles in young and old spontaneously hypertensive rats (SHR).
• To assess how captopril influences cerebral blood flow (CBF) autoregulation and arteriolar structure under hypotensive conditions.

Main Methods:

• Cerebral blood flow and arteriolar internal diameter were measured in Wistar Kyoto rats and SHR (untreated or captopril-treated).
• Animals underwent stepwise hypotension to assess autoregulation.
• Cerebral arteriolar cross-sectional area and external diameter were measured after deactivation.

Main Results:

• Captopril treatment decreased the lower limit of cerebral blood flow autoregulation in SHR.
• ACEI treatment reduced the cross-sectional area of the cerebral arteriolar wall in SHR.
• Captopril increased cerebral arteriolar external diameter in SHR and attenuated increases in arteriolar distensibility.

Conclusions:

• ACEIs, such as captopril, attenuate inward remodeling (eutrophic and hypertrophic) of cerebral arterioles in both young and old SHR.
• This remodeling attenuation by ACEIs leads to a reduced lower limit of cerebral blood flow autoregulation.