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Heme oxygenase-1-derived bilirubin ameliorates postischemic myocardial dysfunction
J E Clark1, R Foresti, P Sarathchandra
1Restoration of Appearance and Function Trust, Institute of Plastic Surgery, Mount Vernon Hospital, Northwood HA6 2RN, United Kingdom.
American Journal of Physiology. Heart and Circulatory Physiology
|February 9, 2000
Summary
Increased cardiac bilirubin, derived from heme oxygenase-1 (HO-1), protects the heart against reperfusion injury. Supplementing bilirubin significantly restored heart function and reduced damage after ischemia.
Area of Science:
- Biochemistry
- Cardiovascular Physiology
- Antioxidant Research
Background:
- Bilirubin is an endogenous antioxidant produced during heme degradation by heme oxygenase.
- Oxidative stress and reperfusion injury significantly impact myocardial function.
Purpose of the Study:
- To investigate the protective role of elevated cardiac bilirubin against post-ischemic myocardial dysfunction.
- To elucidate the contribution of heme oxygenase-1 (HO-1) derived bilirubin in cardioprotection.
Main Methods:
- Isolated rat hearts perfused using the Langendorff technique to assess recovery post-ischemia/reperfusion.
- Upregulation of HO-1 using hemin and inhibition of heme oxygenase activity using tin protoporphyrin IX.
- Measurement of myocardial function, infarct size, and mitochondrial damage.
Main Results:
- Hemin-induced HO-1 upregulation improved post-ischemic myocardial function and reduced infarct size.
- Heme oxygenase inhibition abolished these protective effects and exacerbated cardiac injury.
- Exogenous bilirubin administration restored cardiac function and minimized damage, even at nanomolar concentrations.
Conclusions:
- HO-1-derived bilirubin plays a crucial role in protecting the heart against reperfusion injury.
- Targeting the heme oxygenase pathway or bilirubin levels may offer therapeutic strategies for myocardial protection.