Involvement of calcium-sensing receptor in ischemia/reperfusion-induced apoptosis in rat cardiomyocytes.
The calcium-sensing receptor (CaR) is a seven-transmembrane G-protein coupled receptor, which activates intracellular effectors, for example, it causes inositol phosphate (IP) accumulation to increase the release of intracellular calcium. Although intracellular calcium overload has been implicated in the cardiac ischemia/reperfusion (I/R)-induced apoptosis, the role of CaR in the induction of apoptosis has not been fully understood. This study tested the hypothesis that CaR is involved in I/R cardiomyocyte apoptosis by increasing [Ca2+]i. The isolated rat hearts were subjected to 40-min ischemia followed by 2 h of reperfusion, meanwhile GdCl3 was added to reperfusion solution. The expression of CaR increased at the exposure to GdCl3 during I/R. By laser confocal microscopy, it was observed that the intracellular calcium was significantly increased and exhibited a Deltapsim, as monitored by 5,5',6,6'-tetrachloro-1,1',3,3'- tetraethylbenzimidazolcarbocyanine iodide (JC-1) during reperfusion with GdCl3. Furthermore, the number of apoptotic cells was significantly increased as shown by TUNEL assay. Typical apoptotic cells were observed with transmission electron microscopy in I/R with GdCl3 but not in the control group. The expression of cytosolic cytochrome c and activated caspase-9 and caspase-3 was significantly increased whereas the expression of mitochondrial cytochrome c significantly decreased in I/R with GdCl3 in comparison to the control. In conclusion, these results suggest that CaR is involved in the induction of cardiomyocyte apoptosis during ischemia/reperfusion through activation of cytochrome c-caspase-3 signaling pathway.
Zhang
Wei-hua
WH
Department of Pathophysiology, Harbin Medical University, Harbin 150086, China.
Fu
Song-bin
SB
Lu
Fang-hao
FH
Wu
Bo
B
Gong
Dong-mei
DM
Pan
Zhen-wei
ZW
Lv
Yan-jie
YJ
Zhao
Ya-jun
YJ
Li
Quan-Feng
QF
Wang
Rui
R
Yang
Bao-feng
BF
Xu
Chang-qing
CQ
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000502:physiology; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000096:biosynthesis; D045304:Cytochromes c / Q000378:metabolism; D005682:Gadolinium / Q000494:pharmacology; D008297:Male; D018613:Microscopy, Confocal; D008929:Mitochondria, Heart / Q000378:metabolism; D015428:Myocardial Reperfusion Injury / Q000503:physiopathology*; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000187:drug effects; D051381:Rats; D044169:Receptors, Calcium-Sensing / Q000502:physiology*
D020746:Calcium Channels, L-Type; D044169:Receptors, Calcium-Sensing; D045304:Cytochromes c; D005682:Gadolinium; C505410:Casp3 protein, rat; C506435:Casp9 protein, rat; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases; C038958:gadolinium chloride; D002118:Calcium