Dynamic exercise training prevents exercise pressor reflex overactivity in spontaneously hypertensive rats

Area of Science:

• Cardiovascular Physiology
• Exercise Physiology
• Hypertension Research

Background:

• Cardiovascular responses to exercise are heightened in hypertension.
• This heightened response is linked to an abnormal skeletal muscle exercise pressor reflex (EPR).
• Exercise training is known to attenuate EPR in healthy individuals and heart failure models, but its effect in hypertension is unclear.

Purpose of the Study:

• To investigate whether exercise training mitigates the overactive EPR in spontaneously hypertensive rats (SHR).
• To test the hypothesis that exercise training diminishes the exaggerated EPR in hypertension.

Main Methods:

• Compared untrained (WKYUT, SHRUT) and exercise-trained (WKYET, SHRET) Wistar-Kyoto rats and spontaneously hypertensive rats.
• Assessed mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA) responses to muscle contraction, passive stretch, and capsaicin administration.
• Utilized decerebration to isolate reflex responses.

Main Results:

• Exercise training significantly reduced baseline MAP in SHRET compared to SHRUT.
• Exercise training markedly attenuated the exaggerated increases in MAP and RSNA during muscle contraction in SHRET versus SHRUT.
• Similar attenuating effects of training were observed for passive stretch and capsaicin-induced responses in SHRET.

Conclusions:

• Abnormally exaggerated EPR function in hypertensive rats is significantly diminished by exercise training.
• Exercise training offers physiological benefits by reducing exercise pressor reflex overactivity in hypertension.
• These findings highlight a potential mechanism through which exercise impacts cardiovascular regulation in hypertension.