Critical role of free cytosolic calcium, but not uncoupling, in mitochondrial permeability transition and cell death induced by diclofenac oxidative metabolites in immortalized human hepatocytes

2006 ◽  
Vol 217 (3) ◽  
pp. 322-331 ◽  
Author(s):  
Miao Shan Lim ◽  
Priscilla L.K. Lim ◽  
Rashi Gupta ◽  
Urs A. Boelsterli
Keyword(s):  
Cell Death ◽  
Mitochondrial Permeability Transition ◽  
Critical Role ◽  
Permeability Transition ◽  
Cytosolic Calcium ◽  
Human Hepatocytes ◽  
Mitochondrial Permeability ◽  
Oxidative Metabolites

Role of sarcoplasmic reticulum in mitochondrial permeability transition and cardiomyocyte death during reperfusion

2009 ◽  
Vol 297 (4) ◽  
pp. H1281-H1289 ◽  
Author(s):  
Marisol Ruiz-Meana ◽  
Arancha Abellán ◽  
Elisabet Miró-Casas ◽  
Esperanza Agulló ◽  
David Garcia-Dorado
Keyword(s):  
Cell Death ◽  
Sarcoplasmic Reticulum ◽  
Trypan Blue ◽  
Mitochondrial Permeability Transition ◽  
Critical Role ◽  
Sudden Change ◽  
Permeability Transition ◽  
Rat Cardiomyocytes ◽  
Mitochondrial Permeability ◽  
Calcein Release

There is solid evidence that a sudden change in mitochondrial membrane permeability (mitochondrial permeability transition, MPT) plays a critical role in reperfusion-induced myocardial necrosis. We hypothesized that sarcoplasmic reticulum (SR) Ca2+ cycling may induce partial MPT in microdomains of close anatomic proximity between mitochondria and SR, resulting in hypercontracture and cell death. MPT (mitochondrial calcein release), cell length, and sarcolemmal rupture (Trypan blue and lactate dehydrogenase release) were measured in adult rat cardiomyocytes submitted to simulated ischemia (NaCN/2-deoxyglucose, pH 6.4) and reperfusion. On simulated reperfusion, 83 ± 2% of myocytes developed hypercontracture. In 22 ± 6% of cases, hypercontracture was associated with sarcolemmal disruption [Trypan blue(+)]. During simulated reperfusion there was a 25% release of cyclosporin A-sensitive mitochondrial calcein (with respect to total mitochondrial calcein content). Simultaneous blockade of SR Ca2+ uptake and release with thapsigargin and ryanodine, respectively, significantly reduced mitochondrial calcein release, hypercontracture, and cell death during simulated reperfusion. SR Ca2+ blockers delayed mitochondrial Ca2+ uptake in digitonin-permeabilized cardiomyocytes but did not have any effect on isolated mitochondria. Pretreatment with colchicine to disrupt microtubule network reduced the degree of fluorescent overlap between SR and mitochondria and abolished the protective effect of SR Ca2+ blockers on MPT, hypercontracture, and cell death during reperfusion. We conclude that SR Ca2+ cycling during reperfusion facilitates partial mitochondrial permeabilization due to the close anatomic proximity between both organelles, favoring hypercontracture and cell death.

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