%0 Journal Article
%T Increased myocardial SERCA expression in early type 2 diabetes mellitus is insulin dependent: In vivo and in vitro data
%A Sabine Fredersdorf
%A Christian Thumann
%A Wolfram H Zimmermann
%A Roland Vetter
%A Tobias Graf
%A Andreas Luchner
%A G¨¹nter AJ Riegger
%A Heribert Schunkert
%A Thomas Eschenhagen
%A Joachim Weil
%J Cardiovascular Diabetology
%D 2012
%I BioMed Central
%R 10.1186/1475-2840-11-57
%X Zucker Diabetic Fatty rats treated with or without insulin (ZDF£¿¡À£¿Ins, n£¿=£¿13) and lean littermates (controls, n£¿=£¿7) were sacrificed at the age of 19£¿weeks. ZDF£¿+£¿Ins (n£¿=£¿6) were treated with insulin for the last 6£¿weeks of life. Gene expression of Ca2+ ATPase in the cardiac sarcoplasmatic reticulum (SERCA2a, further abbreviated as SERCA) and phospholamban (PLB) were determined by northern blotting. Ca2+ transport of the sarcoplasmatic reticulum (SR) was assessed by oxalate-facilitated 45Ca-uptake in left ventricular homogenates. In addition, isolated neonatal cardiomyocytes were stimulated in cell culture with insulin, glucose or triiodthyronine (T3, positive control). mRNA expression of SERCA and PLB were measured by Taqman PCR. Furthermore, effects of insulin treatment on force of contraction and relaxation were evaluated by cardiomyocytes grown in a three-dimensional collagen matrix (engineered heart tissue, EHT) stimulated for 5£¿days by insulin. By western blot phosphorylations status of Akt was determed and the influence of wortmannin.SERCA levels increased in both ZDF and ZDF£¿+£¿Ins compared to control (control 100£¿¡À£¿6.2 vs. ZDF 152£¿¡À£¿26.6* vs. ZDF£¿+£¿Ins 212£¿¡À£¿18.5*# % of control, *p£¿<£¿0.05 vs. control, #p£¿<£¿0.05 vs. ZDF) whereas PLB was significantly decreased in ZDF and ZDF£¿+£¿Ins (control 100£¿¡À£¿2.8 vs. ZDF 76.3£¿¡À£¿13.5* vs. ZDF£¿+£¿Ins 79.4£¿¡À£¿12.9* % of control, *p£¿<£¿0.05 vs control). The increase in the SERCA/PLB ratio in ZDF and ZDF£¿¡À£¿Ins was accompanied by enhanced Ca2+ uptake to the SR (control 1.58£¿¡À£¿0.1 vs. ZDF 1.85£¿¡À£¿0.06* vs. ZDF£¿+£¿Ins 2.03£¿¡À£¿0.1* ¦Ìg/mg/min, *p£¿<£¿0.05 vs. control). Interestingly, there was a significant correlation between Ca2+ uptake and SERCA2a expression. As shown by in-vitro experiments, the effect of insulin on SERCA2a mRNA expression seemed to have a direct effect on cardiomyocytes. Furthermore, long-term treatment of engineered heart tissue with insulin increased the SERCA/PLB ratio and accelerated relaxation time. Akt was sign
%K Diabetic heart
%K Insulin
%K SERCA expression
%K Relaxation velocity
%U http://www.cardiab.com/content/11/1/57