title: Sympathetic and cardiovascular responses to venous distension in an occluded limb.
abstract: We recently showed that a fixed volume (i.e., 40 ml) of saline infused into the venous circulation of an arterially occluded vascular bed increases muscle sympathetic nerve activity (MSNA) and blood pressure. In the present report, we hypothesized that the volume and rate of infusion would influence the magnitude of the sympathetic response. Blood pressure, heart rate, and MSNA were assessed in 13 young healthy subjects during forearm saline infusions (arrested circulation). The effects of different volumes of saline (i.e., 2%, 3%, 4%, or 5% forearm volume at 30 ml/min) and different rates of infusion (i.e., 5% forearm volume at 10, 20, or 30 ml/min) were evaluated. MSNA and blood pressure responses were linked with the infusion volume. Infusion of 5% of forearm volume evoked greater MSNA responses than did infusion of 2% of forearm volume (Δ11.6 ± 1.9 vs. Δ3.1 ± 1.8 bursts/min and Δ332 ± 105 vs. Δ38 ± 32 units/min, all P < 0.05). Moreover, greater MSNA responses were evoked by saline infusion at 30 ml/min than 10 ml/min (P < 0.05). Sonographic measurements confirmed that the saline infusions induced forearm venous distension. The results suggest that volume and rate of saline infusion are important factors in evoking sympathetic activation. We postulate that venous distension contributes to cardiovascular autonomic adjustment in humans.
authors.affiliation: Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Cui
authors.forename: Urs A
authors.initials: UA
authors.lastname: Leuenberger
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Gao
authors.forename: Lawrence I
authors.initials: LI
authors.lastname: Sinoway
mesh_terms: D000328:Adult; D001132:Arm / Q000098:blood supply; D001794:Blood Pressure / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008099:Liver / Q000187:drug effects / Q000473:pathology; D008297:Male; D018482:Muscle, Skeletal / Q000294:innervation* / Q000502:physiology; D010179:Pancreas / Q000187:drug effects / Q000473:pathology; D012119:Respiration; D012965:Sodium Chloride / Q000008:administration & dosage / Q000494:pharmacology; D013564:Sympathetic Nervous System / Q000502:physiology*; D014661:Vasoconstriction; D014664:Vasodilation / Q000502:physiology*
chemical_list: D012965:Sodium Chloride