title: Effect of P2 receptor blockade with pyridoxine on sympathetic response to exercise pressor reflex in humans.
abstract: During exercise, sympathetic nervous system activity increases and this contributes to an increase in blood pressure (i.e. exercise pressor reflex). Although animal studies suggest that purinergic P2 receptors on thin fibre sensory nerves are stimulated and evoke this reflex, human data are lacking. In this study, young healthy volunteers performed fatiguing isometric handgrip before and after a local infusion of pyridoxine (i.e. vitamin B(6)) into the 'isolated' circulation of the human forearm. Pyridoxine is converted into a P2-purinoceptor antagonist. Muscle sympathetic nerve activity and blood pressure responses to fatiguing handgrip and post-exercise circulatory occlusion were significantly less after pyridoxine than they were before. These effects were not observed after infusion of saline. These data suggest that P2 receptors contribute to the exercise pressor reflex in humans.
authors.affiliation: Penn State Heart and Vascular Institute, Pennsylvania State College of Medicine, Hershey, PA 17033, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Cui
authors.forename: Urs A
authors.initials: UA
authors.lastname: Leuenberger
authors.forename: Cheryl
authors.initials: C
authors.lastname: Blaha
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: King
authors.forename: Lawrence I
authors.initials: LI
authors.lastname: Sinoway
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D058639:Cold-Shock Response / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005260:Female; D018737:Hand Strength / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology; D010543:Peroneal Nerve / Q000502:physiology; D058919:Purinergic P2 Receptor Antagonists / Q000097:blood / Q000494:pharmacology*; D011732:Pyridoxal Phosphate / Q000097:blood; D011736:Pyridoxine / Q000378:metabolism / Q000494:pharmacology*; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult
chemical_list: D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D011732:Pyridoxal Phosphate; D011736:Pyridoxine