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Muscle metaboreflex activation during dynamic exercise evokes epinephrine release resulting in β2‐mediated vasodilation (1172.2)
Author(s) -
Kaur Jasdeep,
Spranger Marty,
Hammond Robert,
Krishnan Abhinav,
Alvarez Alberto,
Augustyniak Robert,
O’Leary Donal
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.1172.2
Subject(s) - vasodilation , blockade , medicine , epinephrine , cardiology , mean arterial pressure , anesthesia , prazosin , hindlimb , ischemia , blood pressure , endocrinology , heart rate , antagonist , receptor
Muscle metaboreflex‐induced increases in mean arterial pressure (MAP) during submaximal dynamic exercise are mediated principally by increases in cardiac output. To what extent, if any, the peripheral vasculature contributes to this rise in MAP is debatable. In several studies we observed that in response to muscle metaboreflex activation (MMA; induced by partial hindlimb ischemia), small but significant vasodilation occurred within the non‐ischemic vasculature (termed non‐ischemic vascular conductance; NIVC). We hypothesized that these increases in NIVC may stem from a metaboreflex‐induced release of epinephrine (Epi) resulting in β2‐mediated dilation. We measured NIVC and arterial plasma Epi levels in chronically instrumented dogs during rest, mild exercise (3.2 kph) and MMA before and after β‐blockade (propanolol; 2 mg/kg), α‐blockade (prazosin; 50 µg/kg) and α+β‐blockade. Both Epi and NIVC increased significantly from exercise to MMA: 81.9 ± 18.6 to 141.3 ± 22.8 pg/ml and 33.8 ± 1.5 to 37.6 ± 1.6 ml/min/mmHg, respectively. These metaboreflex‐induced increases in NIVC were abolished after β‐blockade (27.6 ± 1.8 to 27.5 ± 1.7 ml/min/mmHg) and potentiated after α‐blockade (36.6 ±2.0 to 49.7 ±2.9 ml/min/mmHg) while α+β‐blockade also abolished any vasodilation (33.7 ± 2.9 to 30.4 ± 1.9ml/min/mmHg). We conclude that MMA at mild exercise induces epinephrine release causing β2‐mediated vasodilation. Grant Funding Source : HL‐55743