Exercise pressor reflex function is augmented in rats with chronic kidney disease

Area of Science:

• Physiology
• Nephrology
• Cardiovascular Science

Background:

• Cardiovascular responses to exercise are often exaggerated in patients with chronic kidney disease (CKD).
• Enhanced sympathetic activation, potentially mediated by the exercise pressor reflex (EPR) originating in contracting muscles, is implicated in this phenomenon.
• Previous human studies suggest an overactive EPR in CKD, but experimental limitations hinder full elucidation.

Purpose of the Study:

• To specifically test the function of the exercise pressor reflex (EPR) in a validated animal model of chronic kidney disease (CKD).

Main Methods:

• Male Sprague-Dawley rats were fed a diet containing 0.25% adenine to induce CKD or a control diet.
• In decerebrate, unanesthetized animals, mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA) responses to EPR activation were assessed.
• Functional components of the EPR, including the mechanoreflex (passive muscle stretch) and metaboreflex (intra-arterial capsaicin), were evaluated.

Main Results:

• CKD rats exhibited significantly higher plasma creatinine levels compared to controls.
• Both MAP and RSNA responses to muscle contraction (EPR activation) were potentiated in CKD rats.
• Responses to passive muscle stretch (mechanoreflex) and intra-arterial capsaicin (metaboreflex) were also significantly augmented in CKD animals.

Conclusions:

• The exercise pressor reflex (EPR), including its mechanoreflex and metaboreflex components, is exaggerated in a rat model of chronic kidney disease (CKD).
• This exaggerated EPR contributes to heightened pressor responses and sympathetic overactivation during muscle contraction in CKD.
• Findings suggest augmented EPR, mechanoreflex, and metaboreflex function in the context of CKD.