Exercise Pressor Reflex Contributes to the Cardiovascular Abnormalities Characterizing: Hypertensive Humans During...

Area of Science:

• Cardiovascular Physiology
• Exercise Physiology
• Hypertension Research

Background:

• Hypertension is associated with abnormal circulatory responses during exercise.
• The exercise pressor reflex, mediated by muscle afferents, influences cardiovascular adjustments to physical activity.

Purpose of the Study:

• To investigate the impact of hypertension on circulatory responses during exercise.
• To determine the role of the exercise pressor reflex in the cardiovascular abnormalities observed in hypertension.

Main Methods:

• Eight hypertensive and eight normotensive individuals performed knee-extensor exercise.
• Circulatory responses (femoral blood flow, vascular conductance, cardiac output, mean arterial pressure) were measured under control conditions and during lumbar intrathecal fentanyl infusion to impair muscle afferent feedback.

Main Results:

• Hypertensive individuals exhibited exaggerated mean arterial pressure (MAP) and reduced leg blood flow (Q_L) and vascular conductance during exercise compared to normotensive individuals.
• Impairing muscle afferent feedback with fentanyl significantly reduced MAP during exercise in hypertensive individuals more than in normotensive individuals.
• Fentanyl administration normalized Q_L and leg vascular conductance in hypertensive individuals to levels seen in normotensive individuals under control conditions, suggesting the exercise pressor reflex is responsible for impaired peripheral hemodynamics.

Conclusions:

• Abnormalities in the exercise pressor reflex significantly contribute to exaggerated MAP responses during exercise in hypertension.
• The exercise pressor reflex plays a crucial role in the impaired peripheral hemodynamic adjustments observed during exercise in hypertensive patients.