title: Rat model of exercise-induced cardiac hypertrophy: hemodynamic characterization using left ventricular pressure-volume analysis.
abstract: Long-term exercise training is associated with characteristic structural and functional changes of the myocardium, termed athlete's heart. Several research groups investigated exercise training-induced left ventricular (LV) hypertrophy in animal models; however, only sporadic data exist about detailed hemodynamics. We aimed to provide functional characterization of exercise-induced cardiac hypertrophy in a rat model using the in vivo method of LV pressure-volume (P-V) analysis. After inducing LV hypertrophy by swim training, we assessed LV morphometry by echocardiography and performed LV P-V analysis using a pressure-conductance microcatheter to investigate in vivo cardiac function. Echocardiography showed LV hypertrophy (LV mass index: 2.41 ± 0.09 vs. 2.03 ± 0.08 g/kg, P < 0.01), which was confirmed by heart weight data and histomorphometry. Invasive hemodynamic measurements showed unaltered heart rate, arterial pressure, and LV end-diastolic volume along with decreased LV end-systolic volume, thus increased stroke volume and ejection fraction (73.7 ± 0.8 vs. 64.1 ± 1.5%, P < 0.01) in trained versus untrained control rats. The P-V loop-derived sensitive, load-independent contractility indexes, such as slope of end-systolic P-V relationship or preload recruitable stroke work (77.0 ± 6.8 vs. 54.3 ± 4.8 mmHg, P = 0.01) were found to be significantly increased. The observed improvement of ventriculoarterial coupling (0.37 ± 0.02 vs. 0.65 ± 0.08, P < 0.01), along with increased LV stroke work and mechanical efficiency, reflects improved mechanoenergetics of exercise-induced cardiac hypertrophy. Despite the significant hypertrophy, we observed unaltered LV stiffness (slope of end-diastolic P-V relationship: 0.043 ± 0.007 vs. 0.040 ± 0.006 mmHg/μl) and improved LV active relaxation (τ: 10.1 ± 0.6 vs. 11.9 ± 0.2 ms, P < 0.01). According to our knowledge, this is the first study that provides characterization of functional changes and hemodynamic relations in exercise-induced cardiac hypertrophy.
authors: Heart Center, Semmelweis University, Budapest, Hungary. radovitstamas@yahoo.com
authors: Tamás
authors: T
authors: Radovits
authors: Attila
authors: A
authors: Oláh
authors: Árpád
authors: Á
authors: Lux
authors: Balázs Tamás
authors: BT
authors: Németh
authors: László
authors: L
authors: Hidi
authors: Ede
authors: E
authors: Birtalan
authors: Dalma
authors: D
authors: Kellermayer
authors: Csaba
authors: C
authors: Mátyás
authors: Gábor
authors: G
authors: Szabó
authors: Béla
authors: B
authors: Merkely
mesh_terms: D000818:Animals; D001794:Blood Pressure; D059267:Cardiomegaly, Exercise-Induced / Q000502:physiology*; D006339:Heart Rate; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D008297:Male; D023421:Models, Animal; D009200:Myocardial Contraction; D051381:Rats; D017208:Rats, Wistar; D013318:Stroke Volume; D013550:Swimming; D014463:Ultrasonography; D016277:Ventricular Function, Left
keywords: cardiac mechanoenergetics; diastolic function; exercise-induced cardiac hypertrophy; pressure-volume analysis; systolic function