Autonomic control of heart rate by metabolically sensitive skeletal muscle afferents in humans

摘要: Isolated activation of metabolically sensitive skeletal muscle afferents (muscle metaboreflex) using post-exercise ischaemia (PEI) following handgrip partially maintains exercise-induced increases in arterial blood pressure (BP) and sympathetic nerve activity (SNA), while heart rate (HR) declines towards resting values. Although masking metaboreflex-mediated cardiac SNA by parasympathetic reactivation during PEI has been suggested, this not directly tested humans. In nine male subjects (23 ± 5 years) the metaboreflex was activated moderate (PEI-M) high (PEI-H) intensity isometric performed at 25% 40% maximum voluntary contraction, under control (no drug), blockade (glycopyrrolate) β-adrenergic (metoprolol or propranalol) conditions, beat-to-beat HR BP were continuously measured. During PEI-M, slightly elevated from rest (+3 2 beats min−1); however, elevation abolished with (P 0.05 vs. control). similarly increased PEI-M further PEI-H < 0.05) all conditions. Collectively, these findings suggest that humans; it requires a robust to offset influence on rate.