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


RESULTS
Ventricular microsomal triglyceride transfer protein (P=0.02) and apoB (P=0.04) mRNA levels were both approximately 2-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.
Nielsen
Lars B
LB
Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Denmark. larsbo@rh.dk
Perko
Mario
M
Arendrup
Henrik
H
Andersen
Claus B
CB
D000368:Aged; D000369:Aged, 80 and over; D001055:Apolipoproteins B / Q000235:genetics; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics; D009202:Cardiomyopathies / Q000235:genetics / Q000378:metabolism* / Q000601:surgery; D002352:Carrier Proteins / Q000235:genetics*; D001026:Coronary Artery Bypass; D004268:DNA-Binding Proteins / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics*; D006352:Heart Ventricles / Q000737:chemistry / Q000378:metabolism / Q000601:surgery; D006801:Humans; D000860:Hypoxia / Q000235:genetics / Q000378:metabolism*; D008074:Lipoproteins / Q000096:biosynthesis; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000737:chemistry* / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D051780:Sterol Regulatory Element Binding Protein 1; D014157:Transcription Factors; D014280:Triglycerides / Q000378:metabolism*; D016276:Ventricular Function
D001055:Apolipoproteins B; D022762:CCAAT-Enhancer-Binding Proteins; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D008074:Lipoproteins; D012333:RNA, Messenger; C497387:SREBF1 protein, human; D051780:Sterol Regulatory Element Binding Protein 1; D014157:Transcription Factors; D014280:Triglycerides; C106092:microsomal triglyceride transfer protein