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Stress Responses Initiated in Cardiomyocytes during Hypothermia‐Induced Rewarming Shock
Author(s) -
Schaible Niccole,
Han Young Soo,
Zaidan Louai,
Arteaga Grace,
Tveita Torkjel,
Sieck Gary
Publication year - 2015
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.29.1_supplement.946.5
Subject(s) - hypothermia , endoplasmic reticulum , reactive oxygen species , intracellular , cytosol , oxidative stress , membrane potential , medicine , biology , chemistry , microbiology and biotechnology , biophysics , biochemistry , enzyme
Rewarming shock following accidental hypothermia is a potentially fatal scenario involving cardiac dysfunction. Previously our lab demonstrated that rewarming shock results in a decrease in Ca 2+ sensitivity of contraction in cardiac muscle due to an increase in cTnI phosphorylation. In this study, we hypothesized that rewarming shock initiates a cascade of intracellular events including reactive oxygen species (ROS) formation, endoplasmic reticulum (ER) stress, and mitochondrial disruption. Isolated cardiomyocytes from Sprague‐Dawley rats were exposed to a hypothermia/rewarming protocol (cooled for 1 h, held at 17 o C for 30 min, rewarmed for 1 h) that results in contractile dysfunction indicated by an increase in cytosolic Ca 2+ and reduced cell shortening measured using an IonOptix system. Rewarming shock increased ROS levels measured by an HPLC‐based dihydroethidium assay and by MitoSox fluorescence. Hypothermia/rewarming was also associated with ER stress indicated by increased expression of ER stress markers (Grp78, PERK, and CHOP) measured by Western blot. Finally, rewarming shock was associated with mitochondrial disruption evidenced by mitochondrial membrane depolarization (decreased in TMRM fluorescence) and by an increase in cytosolic cytochrome c (measured by Western blot). Our results support our overall hypothesis and suggest that these ER and mitochondrial intracellular events may underlie myocardial contractile dysfunction following hypothermia/rewarming. Supported by NIH Grant 5T32HL105355‐02 (GCS)