title: Exercise training attenuates chemoreflex-mediated reductions of renal blood flow in heart failure.
abstract: In chronic heart failure (CHF), carotid body chemoreceptor (CBC) activity is increased and contributes to increased tonic and hypoxia-evoked elevation in renal sympathetic nerve activity (RSNA). Elevated RSNA and reduced renal perfusion may contribute to development of the cardio-renal syndrome in CHF. Exercise training (EXT) has been shown to abrogate CBC-mediated increases in RSNA in experimental heart failure; however, the effect of EXT on CBC control of renal blood flow (RBF) is undetermined. We hypothesized that CBCs contribute to tonic reductions in RBF in CHF, that stimulation of the CBC with hypoxia would result in exaggerated reductions in RBF, and that these responses would be attenuated with EXT. RBF was measured in CHF-sedentary (SED), CHF-EXT, CHF-carotid body denervation (CBD), and CHF-renal denervation (RDNX) groups. We measured RBF at rest and in response to hypoxia (FiO2 10%). All animals exhibited similar reductions in ejection fraction and fractional shortening as well as increases in ventricular systolic and diastolic volumes. Resting RBF was lower in CHF-SED (29 ± 2 ml/min) than in CHF-EXT animals (46 ± 2 ml/min, P < 0.05) or in CHF-CBD animals (42 ± 6 ml/min, P < 0.05). In CHF-SED, RBF decreased during hypoxia, and this was prevented in CHF-EXT animals. Both CBD and RDNX abolished the RBF response to hypoxia in CHF. Mean arterial pressure increased in response to hypoxia in CHF-SED, but was prevented by EXT, CBD, and RDNX. EXT is effective in attenuating chemoreflex-mediated tonic and hypoxia-evoked reductions in RBF in CHF.
authors.affiliation: Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and.
authors.forename: Noah J
authors.initials: NJ
authors.lastname: Marcus
authors.affiliation: Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and.
authors.forename: Carolin
authors.initials: C
authors.lastname: Pügge
authors.affiliation: Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and.
authors.forename: Jai
authors.initials: J
authors.lastname: Mediratta
authors.affiliation: Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and.
authors.forename: Alicia M
authors.initials: AM
authors.lastname: Schiller
authors.affiliation: Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and Laboratory of Cardiorespiratory Control, Universidad Autónoma de Chile, Santiago, Chile.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Del Rio
authors.affiliation: Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and.
authors.forename: Irving H
authors.initials: IH
authors.lastname: Zucker
authors.affiliation: Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and.
authors.forename: Harold D
authors.initials: HD
authors.lastname: Schultz
mesh_terms: D000818:Animals; D062186:Arterial Pressure; D002344:Carotid Body / Q000503:physiopathology*; D003714:Denervation; D004195:Disease Models, Animal; D005081:Exercise Therapy; D006333:Heart Failure / Q000503:physiopathology / Q000628:therapy*; D000860:Hypoxia / Q000503:physiopathology; D007668:Kidney / Q000098:blood supply* / Q000294:innervation*; D008297:Male; D009200:Myocardial Contraction; D011817:Rabbits; D012018:Reflex; D012079:Renal Circulation; D013318:Stroke Volume; D013997:Time Factors; D016277:Ventricular Function, Left
keywords: carotid chemoreflex; exercise training; heart failure; renal blood flow