Increase of intracellular Ca(2+) during ischemia/reperfusion injury of heart is mediated by cyclic ADP-ribose.
While the molecular mechanisms by which oxidants cause cytotoxicity are still poorly understood, disruption of Ca(2+) homeostasis appears to be one of the critical alterations during the oxidant-induced cytotoxic process. Here, we examined the possibility that oxidative stress may alter the metabolism of cyclic ADP-ribose (cADPR), a potent Ca(2+)-mobilizing second messenger in the heart. Isolated heart perfused by Langendorff technique was subjected to ischemia/reperfusion injury and endogenous cADPR level was determined using a specific radioimmunoassay. Following ischemia/reperfusion injury, a significant increase in intracellular cADPR level was observed. The elevation of cADPR content was closely correlated with the increase in ADP-ribosyl cyclase activity. Inclusion of oxygen free radical scavengers, 2,2,6,6-tetramethyl-1-piperidinyloxy and mannitol, in the reperfusate prevented the ischemia/reperfusion-induced increases in cADPR level and the ADP-ribosyl cyclase activity. Exposure of isolated cardiomyocytes to t-butyl hydroperoxide increased the ADP-ribosyl cyclase activity, cADPR level, and intracellular Ca(2+) concentration ([Ca(2+)](i)) and consequently resulting in cell lethal damage. The oxidant-induced elevation of [Ca(2+)](i) as well as cell lethal damage was blocked by a cADPR antagonist, 8-bromo-cADPR. These results provide evidence for involvement of cADPR and its producing enzyme in alteration of Ca(2+) homeostasis during the ischemia/reperfusion injury of the heart.
Xie
Guang-Hua
GH
Department of Biochemistry, Chonbuk National University Medical School, Chonju 561-182, South Korea.
Rah
So-Young
SY
Yi
Kye Sook
KS
Han
Myung Kwan
MK
Chae
Soo Wan
SW
Im
Mie-Jae
MJ
Kim
Uh-Hyun
UH
D036541:ADP-ribosyl Cyclase / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002470:Cell Survival; D002478:Cells, Cultured; D036563:Cyclic ADP-Ribose / Q000378:metabolism*; D016166:Free Radical Scavengers / Q000494:pharmacology; D006321:Heart / Q000187:drug effects; D015428:Myocardial Reperfusion Injury / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism; D009924:Organ Culture Techniques; D018384:Oxidative Stress; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D015290:Second Messenger Systems
D016166:Free Radical Scavengers; D017382:Reactive Oxygen Species; D036563:Cyclic ADP-Ribose; D036541:ADP-ribosyl Cyclase; D002118:Calcium