title: Regional sympathetic denervation affects the relation between canine local myocardial blood flow and oxygen consumption.
abstract: Myocardial blood flow and oxygen consumption are heterogeneously distributed. Perfusion and myocardial oxygen consumption are closely correlated in the normal heart. It is unknown how this metabolism-perfusion relation is influenced by sympathetic denervation. We investigated this question in seven chloralose-anaesthetized dogs, 3-4 weeks after regional sympathetic denervation of the left circumflex coronary artery area of supply of the left ventricle. Measurements were made of local myocardial blood flow (MBF, in ml min(-1) (g dry wt)(-1)), measured with microspheres, and myocardial oxygen consumption ( , in mumol min(-1) (g dry wt)(-1)) in the same location, calculated from the (13)C spectrum of tissue extracts after intracoronary infusion of 3-(13)C-lactate. Since both innervated and denervated regions are subject to the same arterial pressure, lower blood flow indicates higher resistance. Mean MBF was 5.56 ml min(-1) (g dry wt)(-1) (heterogeneity of 3.47 ml min(-1) (g dry wt)(-1)) innervated, 7.48 ml min(-1) (g dry wt)(-1) (heterogeneity of 3.62 ml min(-1) (g dry wt)(-1)) denervated (n.s.). Significant linear relations were found between MBF and M Vo2 of individual samples within the innervated and denervated regions. The slopes of these relations were not significantly different, but the adjusted mean was significantly higher in the denervated regions (+1.92 ml min(-1) (g dry wt)(-1), an increase of 38% of the mean MBF at the pooled mean M Vo2, P = 0.028, ANCOVA). The ratio MBF/M Vo2(in ml micromol(-1)) was significantly higher, being 0.296 +/- 0.167 ml micromol(-1) in the denervated region compared with the innervated region, 0.216 +/- 0.126 ml micromol(-1), P = 0.0182, Mann-Whitney U test. These results indicate that sympathetic tone under chloralose anaesthesia imposes a moderate vasoconstrictive effect in the myocardium that is not detected by comparison of the mean blood flow or resistance.
authors.affiliation: Laboratory for Physiology, Institute for Cardiovascular Research (ICaR-VU), VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: David J C
authors.initials: DJ
authors.lastname: Alders
authors.forename: Richard N
authors.initials: RN
authors.lastname: Cornelussen
authors.forename: Frits W
authors.initials: FW
authors.lastname: Prinzen
authors.forename: Patricia A C
authors.initials: PA
authors.lastname: Specht
authors.forename: Mark I M
authors.initials: MI
authors.lastname: Noble
authors.forename: Angela J
authors.initials: AJ
authors.lastname: Drake-Holland
authors.forename: Frans J J
authors.initials: FJ
authors.lastname: de Kanter
authors.forename: Johannes H G M
authors.initials: JH
authors.lastname: van Beek
mesh_terms: D000818:Animals; D002247:Carbon Isotopes; D002395:Catecholamines / Q000378:metabolism; D002952:Citric Acid Cycle / Q000502:physiology; D003326:Coronary Circulation; D004285:Dogs; D006321:Heart / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D007773:Lactates / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology*; D012039:Regional Blood Flow / Q000502:physiology; D013562:Sympathectomy; D013564:Sympathetic Nervous System / Q000502:physiology* / Q000601:surgery; D014661:Vasoconstriction
chemical_list: D002247:Carbon Isotopes; D002395:Catecholamines; D007773:Lactates