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Overexpression of TRPC3 increases apoptosis in response to ischemia/reperfusion but not TNF‐α in adult mouse cardiomyocytes
Author(s) -
Shan Dan,
Marchase Richard B,
Chatham John C
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a865-b
Subject(s) - calpain , apoptosis , annexin , trpc3 , endocrinology , medicine , ischemia , chemistry , transient receptor potential channel , viability assay , annexin a5 , programmed cell death , microbiology and biotechnology , biology , receptor , biochemistry , enzyme , trpc
Capacitative calcium entry (CCE) , attributed to transient receptor potential (TRP) proteins, has been shown to be important in regulating cardiomyocyte hypertrophy. Increased cytosolic Ca 2+ also plays a critical role in mediating cell death in response to ischemia/reperfusion (I/R) injury. Therefore we tested the hypothesis that overexpression of TRPC3 in cardiomyocytes will increase sensitivity to I/R injury. Adult cardiomyocytes isolated from wild‐type (WT) mice and from mice over expressing TRPC3 in the heart (TG) were subject to 90 min ischemia and 3hr reperfusion. After I/R viability was 51±1% in WT and 42±5% in TG (p<0.05). There was no significant difference in necrosis between WT and TG groups; however, apoptosis assessed by annexin‐V was markedly increased in TG (32±1%) compared to WT (21±3%; p<0.05). Treatment with SKF96365 (0.5μM), an inhibitor of CCE, significantly improved cellular viability (54±4%) and decreased apoptosis (15±4%) in TG group, whereas the L‐type Ca 2+ channel inhibitor verapamil (10μM) had no effect. Calpain‐mediated cleavage of α‐fodrin was increased ~3‐fold in the TG group following I/R compared to WT (p<0.05). In contrast to I/R, there was no difference between WT and TG groups in apoptosis induced by TNF‐α (10ng/ml for 2 and 18 hrs). These results suggest that Ca 2+ entry via TRP may play a role in cardiomyocyte apoptosis following I/R due at least in part by increased calpain activation. (Supported by NIH grants HL076165, HL079364, HL‐077100).