Sarcoplasmic reticulum remodeling in cardiomyocytes from patients with ischemic heart disease associated with type 2 diabetes mellitus

Aim. The aim of the study was to investigate the function of sarcoplasmic reticulum (SR) in cardiomyocytes from patients with ischemic heart disease (IHD) associated with type 2 diabetes mellitus (T2DM). Materials and Methods. The study was performed with right atrial appendage trabeculae from patients with IHD associated with T2DM. SR function was evaluated through changes in the inotropic function of the isolated muscles in isometric contraction regimen during the post-rest test. Ca2+-ATPase (SERCA2a) levels were evaluated by Western blotting. Results. Study showed the existence of two different types of inotropic reaction. The first type was characterized by a preservation of the post-rest twitch amplitude at basal levels in patients with IHD or by an increase in the amplitude in patients with IHD associated with T2DM. The second type was characterized by a significant decrease in the inotropic response in the both groups of patients. Concentration of SERCA2a was higher in the myocardium from patients with the first type of inotropic response, being the highest in patients with T2DM. The myocardium of patients with the second type of inotropic response had low concentration of SERCA2a, without a significant difference between patient groups. Conclusions. Compared with IHD alone, combined development of IHD and short-term T2DM is characterized by preservation of SR Ca2+ transporting function and by higher concentration of SERCA2a, which may be important for defining treatment strategy and prognosis.