RESUMO
ß1-adrenergic receptors (ß1-AR) directly affect on intracardiac hemodynamic and the ability of the heart to tolerate physical activity by regulating its inotropic and chronotropic functions. Severe hypersympathicotonia, specific to coronary artery disease (CAD) and chronic heart failure (HF), leads to impaired functioning of ß1-AR. The aim of this research was to assess the expression level of the ß1-AR ADRB1 gene in the myocardium, to evaluate the ß-adrenergic reactivity of the membrane (ß-ARM) of erythrocytes, and to analyze the association of these parameters with myocardial contractile dysfunction in patients with a myocardial infarction (MI) in the past and without it. The study included 126 patients with chronic CAD. Among the patients, 55.6 % had a history of MI at least 6 months ago. The expression of the ADRB1 gene was assessed using real-time polymerase chain reaction. With this purpose, we isolated RNA from the right atrial appendage, which was excised when a heart-lung machine was connected during a planned coronary bypass surgery. ß-ARM was evaluated in 57 patients. This method is based on the fact of inhibition of hemolysis of erythrocytes, placed in a hyposmotic medium, in the presence of a ß-blocker. Within the whole sample of patients, the expression of the ADRB1 gene is comparable in different functional classes of HF. There was no linear correlation between the expression of the ADRB1 gene and left ventricle ejection fraction (LVEF). In patients with a history of MI, the expression of the ADRB1 gene was elevated when compared to a group of patients without MI (p = 0.017). Patients with a history of MI had higher values of ß-ARM than those without MI (p = 0.017). The reverse correlation between ß-ARM and LVEF (r = -0,570, p = 0,002) was revealed in the group of patients without MI but not in the group of patients with a history of MI (r = -0,137, p = 0,479). In the sample of patients with chronic CAD, in the myocardium of subjects with a history of MI, the relative expression of ADRB1 gene was higher compared to the group of patients without MI. In patients with different functional classes (FC) of HF and with different ejection fraction, both with MI and without it, ADRB1 gene expression was comparable. In the group of patients with a history of MI, an increase in ß-ARM was observed, i.e. decrease in the number or sensitivity of ß-AR. Among patients without MI, an inverse correlation was found between ß-ARM and LVEF.