title: Effects of digoxin on muscle reflexes in normal humans.
abstract: Blockade of the skeletal muscle Na(+)-K(+)-ATPase pump by digoxin could result in a more marked hyperkaliema during a forearm exercise, which in turn could stimulate the mechano- and metaboreceptors. In a randomized, double-blinded, placebo-controlled, and cross-over-design study, we measured mean blood pressure (MBP), heart rate (HR), ventilation (V(E)), oxygen saturation (SpO(2)), muscle sympathetic nerve activity (MSNA), venous plasma potassium and lactic acid during dynamic handgrip exercises, and local circulatory arrest in 11 healthy subjects. Digoxin enhanced MBP during exercise but not during the post-handgrip ischemia and had no effect on HR, V(E), SpO(2), and MSNA. Venous plasma potassium and lactic acid were also not affected by digoxin-induced skeletal muscle Na(+)-K(+)-ATPase blockade. We conclude that digoxin increased MBP during dynamic exercise in healthy humans, independently of changes in potassium and lactic acid. A modest direct sensitization of the muscle mechanoreceptors is unlikely and other mechanisms, independent of muscle reflexes and related to the inotropic effects of digoxin, might be implicated.
authors.affiliation: Department of Cardiology, Erasme University Hospital, Lennik Road, 808, 1070 Anderlecht, Brussels, Belgium. chrisrv.janssen@gmail.com
authors.forename: Christophe
authors.initials: C
authors.lastname: Janssen
authors.forename: Olivier
authors.initials: O
authors.lastname: Lheureux
authors.forename: Sofia
authors.initials: S
authors.lastname: Beloka
authors.forename: Dionysios
authors.initials: D
authors.lastname: Adamopoulos
authors.forename: Robert
authors.initials: R
authors.lastname: Naeije
authors.forename: Philippe
authors.initials: P
authors.lastname: van de Borne
mesh_terms: D002316:Cardiotonic Agents / Q000494:pharmacology; D018592:Cross-Over Studies; D004077:Digoxin / Q000494:pharmacology*; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000502:physiology; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D010919:Placebos; D012026:Reflex, Stretch / Q000187:drug effects* / Q000502:physiology; D055815:Young Adult
chemical_list: D002316:Cardiotonic Agents; D010919:Placebos; D004077:Digoxin
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