4-Hydroxy-2-nonenal induces calcium overload via the generation of reactive oxygen species in isolated rat cardiac myocytes.
BACKGROUND
It has been reported that that the amount of 4-hydroxy-2-nonenal (HNE), which is a major lipid peroxidation product and a cytotoxic aldehyde, is increased in the human failing myocardium. This study was designed to determine whether HNE has a pro-oxidant effect in cardiac myocytes and whether HNE causes Ca(2+) overload.


RESULTS
Exposure to HNE for 10 minutes in the presence of ferric nitrilotriacetate induced the production of hydroxyl radical (.OH) in the rat myocardium as assessed by electron spin resonance spectroscopy, and HNE induced the generation of reactive oxygen species (ROS) in a dose-dependent manner as assessed by 2', 7'-dichlorofluorescein diacetate fluorescence. HNE increased intracellular Ca(2+) concentration ([Ca(2+)](i)) as assessed by fura-2 ratio in a dose- and time-dependent manner. After 20 minutes of HNE (400 micromol/L) exposure, hypercontracture was induced in 67% of the cells. Catalase, an antioxidative enzyme that can decompose hydrogen peroxide (H(2)O(2)), significantly attenuated the increase in [Ca(2+)](i) and completely inhibited hypercontracture. Carvedilol, a beta-blocker with potent antioxidant activity, also significantly attenuated the increase in [Ca(2+)](i) and completely inhibited hypercontracture, but propranolol had no effect on either [Ca(2+)](i) increase or hypercontracture.


CONCLUSIONS
HNE induces the formation of ROS, especially H(2)O(2) and .OH, in cardiomyocytes and subsequently ROS cause intracellular Ca(2+) overload. HNE formation may play an important role as a mediator of oxidative stress in heart failure.
Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan. ichibun@cc.okayama-u.ac.jp
Kazufumi
K
Nakamura
Daiji
D
Miura
Kengo Fukushima
KF
Kusano
Yoshihisa
Y
Fujimoto
Wakako
W
Sumita-Yoshikawa
Soichiro
S
Fuke
Nobuhiro
N
Nishii
Satoshi
S
Nagase
Yoshiki
Y
Hata
Hiroshi
H
Morita
Hiromi
H
Matsubara
Tohru
T
Ohe
Hiroshi
H
Ito
D000447:Aldehydes / Q000633:toxicity*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D008297:Male; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism*
D000447:Aldehydes; D017382:Reactive Oxygen Species; C027576:4-hydroxy-2-nonenal; D002118:Calcium