Expression of Genes and Proteins of the Sarcoplasmic Reticulum [Ca.sup.2+]-Transport Systems in Cardiomyocytes in Concomitant Coronary Heart Disease and Type 2 Diabetes Mellitus

We compared the expression of [Ca.sup.2+]-ATPase (SERCA2a), calsequestrin (CASQ2), ryanodine receptors (RyR2) proteins and their genes (ATP2A2, CASQ2, and RYR2) in coronary heart disease (CHD) patients with and without comorbid type 2 diabetes mellitus. All studies were performed on the right atrial appendages resected during coronary bypass surgeries. Expression of SERCA2a and RyR2 proteins and their ATP2A2 (p=0.046) and RYR2 genes in comorbid pathology was significantly (p=0.042) higher (by 1.2 and 2 times; p=0.025). The expression of CASQ2 protein and its gene did not differ significantly between the groups (p=0.82 and p=0.066, respectively). It was concluded that the expression of SERCA2a and RyR2 proteins and their genes (but not CASQ2 and its gene) is elevated in CHD associated with type 2 diabetes mellitus. Expression of the studied proteins correlated with the expression of their genes. Increased expression of CASQ2 protein and its gene can probably prevent imbalance of the [Ca.sup.2+]-transporting systems in cardiomyocytes and contractile dysfunction of the myocardium, even in CHD associated with type 2 diabetes mellitus. Key Words: ATP2A2, CASQ2, RYR2 gene expression; [Ca.sup.2+]-transporter proteins; cardiomyocyte sarcoplasmic reticulum; coronary heart disease associated with type 2 diabetes mellitus