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Do P2X2/3 and P2X3 receptors play a role in the exercise pressor reflex in cats?
Author(s) -
McCord Jennifer L,
Tsuchimochi Hirotsugu,
Kaufman Marc P
Publication year - 2010
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.24.1_supplement.807.4
Subject(s) - reflex , purinergic receptor , receptor , medicine , endocrinology , ppads , cats , p2 receptor , blockade , reflex bradycardia , agonist , chemistry , blood pressure , baroreceptor , heart rate
The exercise pressor reflex is due to activation of thin fiber afferents within contracting muscle. These afferents are in part stimulated by ATP activation of purinergic 2X (P2X) receptors during contraction. Although many P2X receptor subtypes exist, the ones that contribute to the exercise pressor reflex are unknown. However, P2X 2/3 and P2X 3 receptor subtypes are good candidates as they are located on thin fiber afferents and are known to be involved in sensory neurotransmission. To test the hypothesis that P2X 2/3 and P2X 3 receptors evoke the exercise pressor reflex, we examined the effect of two structurally different P2X 2/3 and P2X 3 antagonists, A‐317491 (10 μg/kg) and RO‐3 (5μg/kg) on the pressor response to popliteal artery injections of α,β methylene ATP, an agonist for P2X 2/3 and P2X 3 receptors, and static contraction of the triceps surae muscles in 4 decerebrated cats. We found that both A‐317491 and RO‐3 reduced the pressor response to α,β methylene ATP injection (before blockade Δ 23 ± 4 mmHg; after blockade Δ 14 ± 5 mmHg; P<0.05), suggesting each antagonist was effective in blocking P2X 2/3 and P2X 3 receptors. In addition, both A‐317491 and RO‐3 reduced the pressor response to contraction (before blockade Δ 30 ± 6 mmHg; after blockade Δ 13 ± 3 mmHg; P<0.05). Our findings, thus far, suggest that P2X 2/3 and P2X 3 receptors contribute to the exercise pressor reflex in cats. NIH grant AR 051503