Endogenous bradykinin activity in Dahl rats

Area of Science:

• Cardiovascular Physiology
• Renal Physiology
• Pharmacology

Background:

• Endogenous bradykinin (BK) is implicated in blood pressure (BP) regulation.
• Dahl-sensitive (DS) and Dahl-resistant (DR) rats are models for salt-sensitive and salt-resistant hypertension, respectively.
• Dietary salt (NaCl) intake significantly impacts BP in these rat models.

Purpose of the Study:

• To investigate the role of endogenous bradykinin (BK) in basal blood pressure (BP) regulation in DS and DR rats under varying NaCl diets.
• To determine how high-salt (H) versus low-salt (L) diets affect BK's influence on BP in these rat models.

Main Methods:

• Four groups of rats were studied: DSH (high salt), DSL (low salt), DRH (high salt), DRL (low salt).
• Endogenous BK activity was assessed using a specific BK antagonist (B4146) infused intraarterially.
• Sensitivity to exogenous BK was evaluated via intraarterial injections after antagonist infusion.

Main Results:

• Dahl-sensitive rats on a high-salt diet (DSH) exhibited significantly higher basal mean BP (MBP) compared to other groups.
• BK antagonist infusion increased MBP in DSL rats, indicating a vasodepressor effect of BK.
• The vasodepressor effect of endogenous BK was significantly reduced in DS rats fed a high-salt diet compared to those on a low-salt diet.

Conclusions:

• Endogenous bradykinin (BK) exerts a vasodepressor effect in Dahl-sensitive rats, particularly when consuming a low-salt diet.
• A high-salt diet suppresses the vasodepressor activity of endogenous BK in Dahl-sensitive rats.
• These findings highlight the interplay between dietary salt, endogenous BK, and blood pressure regulation in salt-sensitive hypertension.