title: Congestive heart failure after myocardial infarction in the rat: cardiac force and spontaneous sarcomere activity.
abstract: The causes of reduced cardiac force development in congestive heart failure (CHF) are still uncertain. We explored the subcellular mechanisms leading to decreased force development in trabeculae from rats with a myocardial infarction. We defined CHF according to clinical and pathological criteria and compared properties of trabeculae from animals with CHF (cMI) to those of animals with a myocardial scar but without evidence of CHF (uMI), and sham-operated animals. The new findings of this study on properties of cMI trabeculae are that (1) maximal twitch force following post-extrasystolic potentiation is unchanged; (2) the sensitivity of cMI trabeculae to [Ca(2+)](o) is increased; (3) spontaneous diastolic sarcomere length (SL) fluctuations (SA) are increased in cMI at all levels of SR Ca(2+) loading; and (4) SA is accompanied by a proportional reduction of F(max). The results suggest that the probability of spontaneous diastolic opening of SR Ca(2+) channels is increased in CHF. These data provide the basis for a novel mechanism underlying systolic and diastolic dysfunction as well as arrhythmias in hearts in CHF. If SA proves to be a component of myocardial dysfunction in human CHF, our thinking about therapy of the patient with CHF may be profoundly changed.
authors.affiliation: Department of Medicine, Faculty of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1 Canada.
authors.forename: A W
authors.initials: AW
authors.lastname: Davidoff
authors.forename: P A
authors.initials: PA
authors.lastname: Boyden
authors.forename: K
authors.initials: K
authors.lastname: Schwartz
authors.forename: J B
authors.initials: JB
authors.lastname: Michel
authors.forename: Y M
authors.initials: YM
authors.lastname: Zhang
authors.forename: M
authors.initials: M
authors.lastname: Obayashi
authors.forename: D
authors.initials: D
authors.lastname: Crabbe
authors.forename: H E D J
authors.initials: HE
authors.lastname: ter Keurs
mesh_terms: D000818:Animals; D006333:Heart Failure / Q000503:physiopathology*; D008297:Male; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000503:physiopathology*; D051381:Rats; D011917:Rats, Inbred Lew; D012518:Sarcomeres / Q000502:physiology*