Change in the membranous lipid composition accelerates lipid peroxidation in young rat hearts subjected to 2 weeks of hypoxia followed by hyperoxia.
BACKGROUND
The effects of chronic hypoxia on cardiac membrane fatty acids and on lipid peroxidation were examined, as well as the effect of l-carnitine (LCAR), which suppresses lipid peroxidation, on this process.


RESULTS
Four-week-old Sprague-Dawley rats were exposed to 10% oxygen for 14 days ("Hypoxia"), and then to 100% oxygen for 12 h (O2). LCAR (200 mg/kg) was administered by intraperitoneal injection daily for 2 weeks. Fatty acid composition, malondialdehyde (MDA) as a lipid peroxidation product, and antioxidants (superoxide dismutase (SOD), glutathione peroxidase and catalase) were measured. The concentration of linoleic acid was lower, and that of docosahexaenoic acid, which has more double bonds than linoleic acid, was increased in hypoxic hearts. SOD activity decreased in hypoxia, whereas MDA was unchanged, but significantly increased in "Hypoxia"+O2. LCAR reduced the increase in MDA, and had no effect on SOD activity or fatty acid composition. The administration of LCAR caused an increase in the ventricular levels of acetylcarnitine.


CONCLUSIONS
These results suggest that chronic hypoxia changes the cardiac fatty acid composition of juvenile rats to fatty acids that contain more double-bonds and reduce SOD activity, and that lipid peroxidation was augmented by exposure to oxygen.
Oka
Tatsujiro
T
Department of Pediatric Cardiology and Nephrology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
Itoi
Toshiyuki
T
Terada
Naoto
N
Nakanishi
Hiroki
H
Taguchi
Ryo
R
Hamaoka
Kenji
K
D000108:Acetylcarnitine / Q000378:metabolism; D000367:Age Factors; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D002331:Carnitine / Q000494:pharmacology; D002374:Catalase / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002908:Chronic Disease; D004195:Disease Models, Animal; D005227:Fatty Acids / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D018496:Hyperoxia / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism*; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013482:Superoxide Dismutase / Q000378:metabolism; D013997:Time Factors
D000975:Antioxidants; D005227:Fatty Acids; D008563:Membrane Lipids; D010743:Phospholipids; D008315:Malondialdehyde; D000108:Acetylcarnitine; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D002331:Carnitine