Cardiomyocyte apoptosis induced by short-term diabetes requires mitochondrial GSH depletion

• Published in: American journal of physiology. Heart and circulatory physiology 2005-08, Vol.289 (2), p.H768-H776
• Main Authors: Ghosh, Sanjoy, Pulinilkunnil, Thomas, Yuen, Gloria, Kewalramani, Girish, An, Ding, Qi, Dake, Abrahani, Ashraf, Rodrigues, Brian
• Format: Article
• Language: English
• Subjects: Animals; Apoptosis; Buthionine Sulfoximine - pharmacology; Caspases - metabolism; Diabetes Mellitus, Experimental - metabolism; Diabetes Mellitus, Experimental - physiopathology; Glutathione - antagonists & inhibitors; Male; Maleates - pharmacology; Mitochondria, Heart - metabolism; Myocardium - metabolism; Myocytes, Cardiac - metabolism; Oxidative Stress; Rats; Rats, Wistar
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.00038.2005

Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada Submitted 13 January 2005 ; accepted in final form 24 March 2005 Oxidative stress due to excessive reactive oxygen species (ROS) and depleted antioxidants such as glutathione (GSH) can give rise to apoptotic cell death in acutely diabetic hearts and lead to heart disease. At present, the source of these cardiac ROS or the subcellular site of cardiac GSH loss [i.e., cytosolic (cGSH) or mitochondrial (mGSH) GSH] has not been completely elucidated. With the use of rotenone (an inhibitor of the electron transport chain) to decrease the excessive ROS in acute streptozotocin (STZ)-induced diabetic rat heart, the mitochondrial origin of ROS was established. Furthermore, mitochondrial damage, as evidenced by loss of membrane potential, increases in oxidative stress, and reduction in mGSH was associated with increased apoptosis via increases in caspase-9 and -3 activities in acutely diabetic hearts. To validate the role of mGSH in regulating cardiac apoptosis, L -buthionine-sulfoximine (BSO; 10 mmol/kg ip), which blocks GSH synthesis, or diethyl maleate (DEM; 4 mmol/kg ip), which inactivates preformed GSH, was administered in diabetic rats for 4 days after STZ administration. Although both BSO and DEM lowered cGSH, they were ineffective in reducing mGSH or augmenting cardiomyocyte apoptosis. To circumvent the lack of mGSH depletion, BSO and DEM were coadministered in diabetic rats. In this setting, mGSH was undetectable and cardiac apoptosis was further aggravated compared with the untreated diabetic group. In a separate group, GSH supplementation induced a robust amplification of mGSH in diabetic rat hearts and prevented apoptosis. Our data suggest for the first time that mGSH is crucial for modulating the cell suicide program in short-term diabetic rat hearts. mitochondria; caspase; oxidative stress; heart; glutathione Address for reprint requests and other correspondence: B. Rodrigues, Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, Univ. of British Columbia, 2146 East Mall, Vancouver, BC, Canada V6T 1Z3 (E-mail: rodrigue{at}interchange.ubc.ca )