AIMS: Brain-type alpha-subunit isoforms of the Na(+) channel are present in various cardiac tissue types and may control pacemaker activity and excitation-contraction coupling. Heart failure (HF) alters pacemaker activity and excitation-contraction coupling. Here, we studied whether HF alters brain-type Na(+) channel properties. METHODS AND RESULTS: HF was induced in rabbits by volume/pressure overload. Na(+) currents of ventricular myocytes were recorded in the cell-attached mode of the patch-clamp technique using macropatches. Macropatch recordings were conducted from the middle portions of myocytes or from intercalated disc regions between cell pairs. Both areas exhibited a fast activating and inactivating current, 8.5 times larger in intercalated disc regions. Tetrodotoxin (TTX) (50 nM) did not block currents in the intercalated disc regions, but did block in the middle portions, indicating that the latter currents were TTX-sensitive brain-type Na(+) currents. Macropatch recordings from these regions were used to study the effects of HF on brain-type Na(+) current. Neither current density nor gating properties (activation, inactivation, recovery from inactivation, slow inactivation) differed between CTR and HF. CONCLUSION: The density and gating properties of brain-type Na(+) current are not altered in our HF model. In the volume/pressure-overload rabbit model of HF, the role of brain-type Na(+) current in HF-induced changes in excitation-contraction coupling is limited.
AIMS: Brain-type alpha-subunit isoforms of the Na(+) channel are present in various cardiac tissue types and may control pacemaker activity and excitation-contraction coupling. Heart failure (HF) alters pacemaker activity and excitation-contraction coupling. Here, we studied whether HF alters brain-type Na(+) channel properties. METHODS AND RESULTS: HF was induced in rabbits by volume/pressure overload. Na(+) currents of ventricular myocytes were recorded in the cell-attached mode of the patch-clamp technique using macropatches. Macropatch recordings were conducted from the middle portions of myocytes or from intercalated disc regions between cell pairs. Both areas exhibited a fast activating and inactivating current, 8.5 times larger in intercalated disc regions. Tetrodotoxin (TTX) (50 nM) did not block currents in the intercalated disc regions, but did block in the middle portions, indicating that the latter currents were TTX-sensitive brain-type Na(+) currents. Macropatch recordings from these regions were used to study the effects of HF on brain-type Na(+) current. Neither current density nor gating properties (activation, inactivation, recovery from inactivation, slow inactivation) differed between CTR and HF. CONCLUSION: The density and gating properties of brain-type Na(+) current are not altered in our HF model. In the volume/pressure-overload rabbit model of HF, the role of brain-type Na(+) current in HF-induced changes in excitation-contraction coupling is limited.
Authors: Priscila Y Sato; Wanda Coombs; Xianming Lin; Oxana Nekrasova; Kathleen J Green; Lori L Isom; Steven M Taffet; Mario Delmar Journal: Circ Res Date: 2011-05-26 Impact factor: 17.367
Authors: Xianming Lin; Nian Liu; Jia Lu; Jie Zhang; Justus M B Anumonwo; Lori L Isom; Glenn I Fishman; Mario Delmar Journal: Heart Rhythm Date: 2011-07-20 Impact factor: 6.343
Authors: Roos F J Marsman; Connie R Bezzina; Fabian Freiberg; Arie O Verkerk; Michiel E Adriaens; Svitlana Podliesna; Chen Chen; Bettina Purfürst; Bastian Spallek; Tamara T Koopmann; Istvan Baczko; Cristobal G Dos Remedios; Alfred L George; Nanette H Bishopric; Elisabeth M Lodder; Jacques M T de Bakker; Robert Fischer; Ruben Coronel; Arthur A M Wilde; Michael Gotthardt; Carol Ann Remme Journal: J Am Coll Cardiol Date: 2013-11-27 Impact factor: 24.094
Authors: Abdennasser Bardai; Robert J Lamberts; Marieke T Blom; Anne M Spanjaart; Jocelyn Berdowski; Sebastiaan R van der Staal; Henk J Brouwer; Rudolph W Koster; Josemir W Sander; Roland D Thijs; Hanno L Tan Journal: PLoS One Date: 2012-08-14 Impact factor: 3.240