Hypoxia induces heat shock protein expression in human coronary artery bypass grafts.
OBJECTIVE
Heat shock proteins (HSPs) are molecular chaperones which are essential for cell survival. Heat shock and hypoxia markedly increase the expression of several HSPs in various tissues, i.e. heart. In our in vitro study, we investigated whether HSPs are inducible in human vessels which are used as coronary artery bypass grafts.


METHODS
We used remnants of the saphenous vein and the internal mammary artery from 34 patients undergoing coronary artery bypass surgery. Each vessel was divided into segments, one for control conditions at 37 degrees C (5% CO(2)-95% air), the remaining ones for thermal (30 min at 42 degrees C) or hypoxic treatment (6 h oxygen deprivation with nitrogen). The expression of Hsp60, Hsp72 and Hsp73 was investigated by immunohistochemistry and Western-blot analysis.


RESULTS
Compared to controls, segments of the saphenous vein undergoing heat treatment showed significantly increased expression of Hsp72 in the intima (P=0.035) and Hsp73 in the media (P=0.003). In the internal mammary artery, Hsp72 and Hsp73 were expressed in the intima at significantly higher levels (P=0.042 each). A 6 h oxygen deprivation with nitrogen resulted in elevated levels of Hsp60 (media: P=0.048), of Hsp72 (intima: P<0.001 and media: P=0.004) and of Hsp73 (intima: P=0.029) in the saphenous vein. In the internal mammary artery, Hsp73 expression was significantly enhanced (intima: P=0.048 and media: P=0.017). The results were confirmed by Western-blot analysis in representative veins.


CONCLUSIONS
These findings demonstrate the common cellular defense mechanism of HSP expression in response to stress in coronary artery bypass grafts. Hypoxia and heat treatment strongly induce Hsp72 and Hsp73 expression in human coronary artery bypass grafts.
Department of Med. Chemistry and Biochemistry, Division of Clinical Biochemistry, University of Innsbruck, Fritz-Pregl-Strasse 3, A-6020, Innsbruck, Austria. angelika.lercher@uibk.ac.at
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A
Hammerer-Lercher
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J
Mair
J
J
Bonatti
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SB
Watzka
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Puschendorf
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Dirnhofer
D000368:Aged; D015153:Blotting, Western; D002352:Carrier Proteins / Q000378:metabolism; D001026:Coronary Artery Bypass; D005260:Female; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006358:Hot Temperature; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D008297:Male; D008323:Mammary Arteries / Q000378:metabolism*; D008875:Middle Aged; D009924:Organ Culture Techniques; D012501:Saphenous Vein / Q000378:metabolism*
D002352:Carrier Proteins; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D050884:HSP72 Heat-Shock Proteins; C494371:HSPA8 protein, human; D006360:Heat-Shock Proteins