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The Degree of Myocardial Injury During the Reperfusion Depends on the Oxygen Surrounding the Isolated Heart During Global Normothermic Ischemia
Author(s) -
Bopassa Jean C.
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.lb586
Subject(s) - ischemia , reperfusion injury , myocardial infarction , oxygen , cardiology , medicine , oxidative stress , cardiac function curve , reactive oxygen species , chemistry , anesthesia , biochemistry , heart failure , organic chemistry
During global ischemia, hearts kept “in air” in a humid chamber require ~120 min of reperfusion to establish the myocardial infarction while hearts “immersed” in a physiological buffer require a shorter reperfusion period ~30 min. As oxidative stress favors myocardial injury during reperfusion, we hypothesized that a higher level of oxygen surrounding hearts “immersed” during ischemia favors the myocardial injury during reperfusion. Isolated mice hearts were perfused using a Langendorff apparatus with Krebs Henseleit (KH) buffer oxygenated with 95%O 2 +5%CO 2 at37°C. Hearts were subjected to 18 min global ischemia and kept “in air” or “immersed” in KH followed by different reperfusion durations (40, 60 or 90 min). Cardiac function was recorded and myocardial infarction assessed by TTC staining. ROS generation was measured in isolated mitochondria after 10 min reperfusion. After 40 min reperfusion, myocardial infarct size was much larger in hearts conserved “immersed” compared to “in air” during ischemia. Furthermore, cardiac functional recovery and infarct size at 40, 60 and 90 min of reperfusion kept increasing with “in air” ischemia while with “immersed” ischemia the values had reached steady‐state at 40 min. The role of oxygen‐induced damage was confirmed by replacing oxygenated‐KH with N 2 ‐bubbled‐KH surrounding the heart during “immersed” ischemia. After 40 min reperfusion, cardiac functional recovery was improved and myocardial infarct size was reduced in the group immersed in KH N 2 ‐bubbled when compared to those in oxygenated KH. Mitochondria ROS production was reduced in the group immersed in N 2 ‐bubbled KH compared to those in oxygenated KH. In conclusion, the level of oxygen surrounding hearts during ischemia determines the injury during the reperfusion.