title: Adenoviral gene transfer of mutant phospholamban rescues contractile dysfunction in failing rabbit myocytes with relatively preserved SERCA function.
abstract: In heart failure (HF) a main factor in reduced contractility is reduced SR Ca2+ content and reversed force-frequency response (FFR), ie, from positive to negative. Our arrhythmogenic rabbit HF model exhibits decreased contractility mainly due to an increase in Na/Ca exchange (NCX) activity (with only modest decrease in SR Ca2+-ATPase (SERCA) function), similar to many end-stage HF patients. Here we test whether phospholamban (PLB) inhibition using a dominant-negative mutant PLB adenovirus (K3E/R14E, AdPLB-dn, with beta-galactosidase adenovirus as control) could enhance SERCA function and restore Ca2+ transients and positive FFR in ventricular myocytes from these HF rabbits. HF myocytes infected with AdPLB-dn (versus control) had enhanced Ca2+ transient amplitude (2.0+/-0.1 versus 1.6+/-0.05 F/Fo at 0.5 Hz, P<0.05) and had a positive FFR, whereas acutely isolated HF myocytes or those infected with Adbetagal had negative FFR. Ca2+ transients declined faster in AdPLB-dn versus Adbetagal myocytes (RT50%: 317+/-29 versus 551+/-90 ms at 0.5 Hz, P<0.05) and had an increased SR Ca2+ load (3.5+/-0.3 versus 2.6+/-0.2 F/Fo at 0.5 Hz, P<0.05), indicative of increased SERCA function. Furthermore, this restoration of function was not due to changes in NCX or SERCA expression. Thus, increasing SERCA activity in failing myocytes by AdPLB-dn gene transfer reversed the contractile dysfunction (and restored positive FFR) by increasing SR Ca2+ load. This approach could enhance contractile function in failing hearts of various etiologies, even here where reduced SERCA activity is not the main dysfunction.
authors.affiliation: Department of Physiology, Loyola University Chicago, Maywood, Ill, USA. ziolo.1@osu.edu
authors.forename: Mark T
authors.initials: MT
authors.lastname: Ziolo
authors.forename: Jody L
authors.initials: JL
authors.lastname: Martin
authors.forename: Julie
authors.initials: J
authors.lastname: Bossuyt
authors.forename: Donald M
authors.initials: DM
authors.lastname: Bers
authors.forename: Steven M
authors.initials: SM
authors.lastname: Pogwizd
mesh_terms: D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D000252:Calcium-Transporting ATPases / Q000502:physiology*; D022761:Gene Transfer, Horizontal; D006333:Heart Failure / Q000503:physiopathology / Q000628:therapy*; D009154:Mutation; D009200:Myocardial Contraction; D032383:Myocytes, Cardiac / Q000502:physiology*; D011817:Rabbits; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D016277:Ventricular Function, Left; D000099211:Phospholamban
chemical_list: D002118:Calcium; D002135:Calcium-Binding Proteins; D000252:Calcium-Transporting ATPases; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D000099211:Phospholamban