Blockade of purinergic 2 receptors attenuates the mechanoreceptor component of the exercise pressor reflex

Angela E. Kindig, Shawn G. Hayes, Marc P. Kaufman

    Research output: Contribution to journalArticle

    29 Scopus citations

    Abstract

    The finding that pyridoxalphosphate-6-azophenyl-2,4-disulfonic acid (PPADS), a P2 antagonist, attenuated the pressor response to calcaneal tendon stretch, a purely mechanical stimulus, raises the possibility that P2 receptors sensitize mechanoreceptors to static contraction of the triceps surae muscles. The mechanical component of the exercise pressor reflex, which is evoked by static contraction, can be assessed by measuring renal sympathetic nerve activity during the first 2-5 s of this maneuver. During this period of time, group III mechanoreceptors often discharge explosively in response to the sudden tension developed at the onset of contraction. In decerebrated cats, we, therefore, examined the effect of PPADS (10 mg/kg) injected into the popliteal artery on the renal sympathetic and pressor responses to contraction and stretch. We found that PPADS significantly attenuated the renal sympathetic response to contraction, with the effect starting 2 s after its onset and continuing throughout its 60-s period. PPADS also significantly attenuated the renal sympathetic nerve response to stretch, but did so after a latency of 10 s. Our findings lead us to conclude that P2 receptors sensitize group III muscle afferents to contraction. The difference in the onset latency between the PPADS-induced attenuation of the renal sympathetic response to contraction and the renal sympathetic response to stretch is probably due to the sensitivities of different populations of group III afferents to ATP released during contraction and stretch.

    Original languageEnglish (US)
    JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
    Volume293
    Issue number5
    DOIs
    StatePublished - Nov 2007

    Keywords

    • ATP
    • Cats
    • Group III muscle afferents
    • Group IV muscle afferents
    • Neural control of the circulation
    • Renal sympathetic nerve activity

    ASJC Scopus subject areas

    • Physiology
    • Cardiology and Cardiovascular Medicine
    • Physiology (medical)

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