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ISSN Печать: 2155-014X
ISSN Онлайн: 2155-0158
Cardiac Pump Function and Contractility upon β-Adrenergic Hyperstimulation in Rats
Краткое описание
In experiments on rats with prolonged (for a month) activation of β-adrenergic receptors, both structural and functional rearrangements in the myocardium were studied. Significant weakening of the pump function of the myocardium, namely: a decrease in the 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) has been found. At the same time, there was two-fold (P < 0.01) increase in the end-diastolic left ventricular pressure and constant of active relaxation by 12.91% (P < 0.05). These changes indicate the presence of diastolic dysfunction of the heart, and its development is associated with both the accumulation of connective tissue elements in the myocardium and an increase in end-diastolic stiffness. It may result in disturbances of the pump function of the heart. Quite surprising to us was the fact of significant increase in myocardial contractility not only while using an agonist of β-adrenergic receptors but also in 26 days after its removal. This fact is evidenced by an increase in maximum rate of pressure development by 49.9% (P < 0.01), as well as end-systolic and maximum elastance of the myocardium increased two and a half times (P < 0.01) and by 42.53% (P < 0.05), respectively. This phenomenon can be explained by compensatory increase in myocardial contractility in these conditions, but it is insufficient to maintain adequate pump function of the heart and, moreover, it may result in depletion of energy resources of the heart.