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Acid sensing ion and epithelial sodium channels contribute to the metaboreceptor component of the exercise pressor reflex
Author(s) -
McCord Jennifer Lockwood,
Tsuchimochi Hirotsugu,
Kaufman Marc P
Publication year - 2009
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.23.1_supplement.787.2
Subject(s) - amiloride , contraction (grammar) , reflex , myogenic contraction , medicine , chemistry , saline , muscle contraction , endocrinology , anesthesia , sodium , smooth muscle , organic chemistry
The exercise pressor reflex is due to activation of thin fiber afferents within contracting muscle. Acid sensing ion channels (ASICs), which are blocked by amiloride, play a role in stimulating the endings of these afferents during contraction. Recently, amiloride had no effect on the mechanoreceptor component of the reflex, prompting us to determine if ASICs contributed to the metaboreceptor component of the exercise pressor reflex. The metaboreceptor component can be assessed by measuring mean arterial pressure during post contraction ischemia when only metabolic afferents are stimulated. We examined the effect of amiloride (0.5 µg/kg) injected into the popliteal artery on the pressor response to and after ischemic static contraction of the triceps surae muscles in 11 decerebrated cats. Amiloride attenuated the pressor response both to ischemic contraction (before amiloride Δ 32 ± 4 mmHg; after amiloride Δ 19 ± 3 mmHg; P<0.05) and to post contraction ischemia (before amiloride Δ 19 ± 3 mmHg; after amiloride Δ 9 ± 3 mmHg; P<0.05). Saline, however, injected as a control, had no effect on the pressor response to ischemic contraction (before saline Δ 24 ± 2 mmHg; after saline Δ 25 ± 4 mmHg; P=0.99) or to post contraction ischemia (before saline Δ 12 ± 2 mmHg; after saline Δ 10 ± 2 mmHg; P=0.97) in 6 cats. Our findings lead us to conclude that ASICs contribute to the metaboreceptor component of the exercise pressor reflex.µ