title: [Interrelation between cardiac pump function disturbances and cardiac contractility after beta-adrenergic hyperstimulation of the heart in rats].
abstract: The complex of structural and functional changes of myocardium was investigated in experiments with rats with chronic beta-adrenergic activation for 1 month. We observed substantial attenuation of myocardial pump function, particularly reduction of stroke volume by 38.50% (P < 0.01), cardiac output by 42.38% (P < 0.01), and ejection fraction by 35.61% (P < 0.01). Furthermore, 2-fold increase of end-diastolic left ventricular pressure (P < 0.01) and rise of active relaxation constant Tau by 12.91% (P < 0.05) were observed. This indicates on an impaired diastolic function of the heart that is associated with accumulation of connective tissue elements in myocardium and increase of its end-diastolic stiffness that finally leads to cardiac pump function disturbances. Surprisingly, myocardial contractility was considerably augmented not only after the treatment with beta-adrenergic agonist but also on the 26th day after drug cessation. This phenomenon is associated with elevation of dP/dt(max) by 49.9% (P < 0.01), 2.5-fold increase of end-systolic elastance (P < 0.01) as well as maximal myocardial elastance by 42.53% (P < 0.05). It can be explained by compensatory influence of increased contractility that nevertheless failed to maintain adequate cardiac pump function and furthermore it may result in depletion of cardiac energy resource.
authors.forename: M O
authors.initials: MO
authors.lastname: Kuz'menko
authors.forename: V B
authors.initials: VB
authors.lastname: Pavliuchenko
authors.forename: L V
authors.initials: LV
authors.lastname: Tumanovs'ka
authors.forename: V Ie
authors.initials: VIe
authors.lastname: Dosenko
authors.forename: O O
authors.initials: OO
authors.lastname: Moĭbenko
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D002302:Cardiac Output / Q000187:drug effects*; D003627:Data Interpretation, Statistical; D005260:Female; D006334:Heart Function Tests; D007545:Isoproterenol / Q000494:pharmacology*; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D016277:Ventricular Function, Left / Q000187:drug effects*
chemical_list: D000318:Adrenergic beta-Agonists; D007545:Isoproterenol