Decreased expression of β₁- and β ₂-adrenoceptors in human diabetic artrial appendage

Background: Using the streptozotocin-induced diabetic rat model, we have recently showed that the expression and function of β₁-adrenoreceptor were decreased in the diabetic rat heart. However, the effect of diabetes on expression of β ₁-adrenoreceptors in human cardiac tissue remains undefined. Therefore, the focus of the present study was to investigate the effect of diabetes on mRNA encoding β₁- and β ₂-ARs in human atrial tissues. Methods: Right atrial appendages from five diabetic (mean age 65 ± 4.5; 4 female, 1 male) and five nondiabetic patients (mean age5 6.2 ± 2.8; 4 male, 1 female) undergoing coronary artery bypass grafting were collected and assayed using reverse transcriptase-polymerase chain reaction (RTPCR) for their mRNA content. No patient from these two groups suffered from acute myocardial infarction and/or failure. All diabetic patients received insulin for at least two years and had been diagnosed as diabetics for at least five years. Results: When compared with levels in nondiabetics, steady state levels of mRNA encoding β ₁-adrenoreceptor decreased by 69.2 ± 7.6 % in diabetic patients while β₂-adrenoreceptor mRNA decreased by 32.2 ± 5.5 % (p < 0.001). Conclusions: Our findings show a decreased expression of β₁- and β₂-adrenoreceptors in human diabetic atrial appendage.