Microsomal triglyceride transfer protein gene expression and triglyceride accumulation in hypoxic human hearts

Objectives-Cardiac myocytes secrete apolipoprotein (apo)B-containing lipoproteins. Their function may be the removal of triglycerides when beta-oxidation of fatty acids is decreased, eg, during hypoxia. To test this hypothesis, we examined heart biopsies from patients undergoing coronary artery bypass graft (CABG, n=13) or valve replacement (n=6) surgery. Methods and Results-Ventricular microsomal triglyceride transfer protein (P=0.02) and apoB (P=0.04) mRNA levels were both approximate to2-fold higher in CABG compared with valve replacement patients. In CABG patients, ventricular microsomal triglyceride transfer protein mRNA levels were negatively associated with the triglyceride content in ventricular myocytes (r=-0.70; P=0.02) and with mRNA levels of sterol regulatory element binding protein-1 (r=-0.74; P=0.004). Conclusions-The results are compatible with the notion that cardiac lipoprotein production is increased in hypoxic human ventricle, possibly as a result of decreased sterol regulatory element binding protein-1 expression. This might attenuate accumulation of triglycerides in cardiac myocytes.