Blood Pressure Changes After Exposures Increasing Angiotensin-Converting Enzyme Activity and After Its Normalization...

Area of Science:

• Cardiovascular Physiology
• Pharmacology
• Biochemistry

Background:

• Angiotensin-converting enzyme (ACE) plays a crucial role in regulating blood pressure (BP) and heart rate (HR).
• Factors like ionizing radiation, NO synthase inhibition, and dexamethasone can influence ACE activity.
• Understanding the interplay between ACE, BP, and HR under various physiological and pathological conditions is vital.

Purpose of the Study:

• To investigate the impact of ionizing radiation, NO synthase inhibition (L-NAME), and dexamethasone on ACE activity, BP, and HR in Wistar male rats.
• To evaluate the effects of dihydroquercetin and enalapril on ACE activity, BP, and HR under these exposure conditions.

Main Methods:

• Wistar male rats were exposed to X-ray irradiation (2.5 Gy).
• ACE activity in aorta sections was measured via Hip-His-Leu hydrolysis.
• BP and HR were recorded non-invasively using a tail-cuff method and PowerLab 8/35 software.
• Rats were treated with L-NAME, dexamethasone, dihydroquercetin, or enalapril.

Main Results:

• Ionizing radiation did not alter ACE activity, BP, or HR.
• Prolonged L-NAME or dexamethasone treatment increased ACE activity, leading to elevated BP. L-NAME also reduced HR.
• Dihydroquercetin partially normalized ACE activity and lowered BP.
• Enalapril normalized L-NAME-induced elevated BP and significantly decreased ACE activity.

Conclusions:

• While ionizing radiation had no discernible effect on ACE activity or hemodynamics, prolonged L-NAME and dexamethasone treatments significantly impacted these parameters.
• Dihydroquercetin demonstrated partial efficacy in mitigating ACE-related hypertension, while enalapril effectively normalized BP and reduced ACE activity.
• These findings highlight the complex regulation of BP and HR by ACE and the potential therapeutic roles of specific inhibitors and natural compounds.