Metallothionein alleviates glutathione depletion-induced oxidative cardiomyopathy in murine hearts.
OBJECTIVE
Antioxidant therapy has shown some promise in critical care medicine in which glutathione depletion and heart failure are often seen in critically ill patients. This study was designed to examine the impact of glutathione depletion and the free radical scavenger, metallothionein (MT), on cardiac function.


METHODS
Friend virus B and MT transgenic mice were given the glutathione synthase inhibitor buthionine sulfoximine (buthionine sulfoximine [BSO], 30 mmol/L) in drinking water for 2 wks.


METHODS
Echocardiographic and cardiomyocyte functions were evaluated, including myocardial geometry, fraction shortening, peak shortening, time-to-90% relengthening (TR90), maximal velocity of shortening/relengthening (+/-dL/dt), intracellular Ca2+ rise, sarcoplasmic reticulum Ca2+ release, and intracellular Ca2+ decay rate. Sacro (endo)plasmic reticulum Ca2+-ATPase function was evaluated by 45Ca uptake. Highly reactive oxygen species, caspase-3, and aconitase activity were detected by fluorescent probe and colorimetric assays.


RESULTS
BSO elicited lipid peroxidation, protein carbonyl formation, mitochondrial damage, and apoptosis. BSO also reduced wall thickness, enhanced end systolic diameter, depressed fraction shortening, peak shortening, +/-dL/dt, sarcoplasmic reticulum Ca2+ release, 45Ca uptake, and intracellular Ca2+ decay, leading to prolonged TR90. BSO-induced mitochondrial loss and myofilament aberration. MT transgene itself had little effect on myocardial mechanics and ultrastructure. However, it alleviated BSO-induced myocardial functional, morphologic, and carbonyl changes. Western blot analysis showed reduced expression of sacro (endo)plasmic reticulum Ca2+-ATPase2a, Bcl-2 and phosphorylated GSK-3beta, enhanced calreticulin, Bax, p53, myosin heavy chain-beta isozyme switch, and IkappaB phosphorylation in FVB-BSO mice, all of which with the exception of p53 were nullified by MT.


CONCLUSIONS
Our findings suggest a pathologic role of glutathione depletion in cardiac dysfunction and the therapeutic potential of antioxidants.
Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, Laramie, WY, USA. jren@uwyo.edu
Jun
J
Ren
Jamie R
JR
Privratsky
Xiaoping
X
Yang
Feng
F
Dong
Edward C
EC
Carlson
D000818:Animals; D019328:Buthionine Sulfoximine / Q000494:pharmacology*; D009202:Cardiomyopathies / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000209:etiology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005978:Glutathione / Q000172:deficiency*; D005981:Glutathione Synthase / Q000037:antagonists & inhibitors; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D008668:Metallothionein / Q000627:therapeutic use*; D051379:Mice; D008822:Mice, Transgenic; D009200:Myocardial Contraction / Q000187:drug effects*; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism*; D014463:Ultrasonography
D004791:Enzyme Inhibitors; D017382:Reactive Oxygen Species; D019328:Buthionine Sulfoximine; D008668:Metallothionein; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D005981:Glutathione Synthase; D005978:Glutathione