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Preconditioning reduces myocardial complement gene expression in vivo.
E J Tanhehco1, K Yasojima, P L McGeer
1Department of Pharmacology, University of Michigan Medical School Ann Arbor, Michigan 48109-0632, USA.
American Journal of Physiology. Heart and Circulatory Physiology
|September 20, 2000
Summary
Preconditioning reduces heart damage after ischemia and reperfusion by decreasing complement system proteins. This protective effect involves ATP-sensitive potassium channels and is key for limiting myocardial injury.
Area of Science:
- Cardiovascular Physiology
- Immunology
- Molecular Biology
Background:
- Ischemia-reperfusion injury (IRI) is a major cause of myocardial damage.
- The complement system plays a role in IRI pathogenesis.
- Preconditioning strategies aim to mitigate IRI.
Purpose of the Study:
- To investigate the effect of preconditioning on the complement system during myocardial IRI in vivo.
- To determine the role of ATP-sensitive potassium (K(ATP)) channels in preconditioning-induced protection against IRI.
Main Methods:
- An in vivo rabbit model of regional myocardial ischemia-reperfusion.
- Preconditioning with intermittent ischemia or a K(ATP) channel opener (diazoxide).
- Assessment of infarct size, complement component mRNA expression (C1q, C1r, C3, C8, C9), and membrane attack complex (MAC) deposition.
Main Results:
- Preconditioning significantly reduced infarct size and complement mRNA expression in the area at risk.
- The K(ATP) channel blocker 5-hydroxydecanoate (5-HD) attenuated the protective effects of preconditioning and partially reversed complement downregulation.
- Western blot confirmed reduced MAC expression in preconditioned hearts.
Conclusions:
- Preconditioning significantly reduces myocardial IRI by downregulating the complement system.
- K(ATP) channels are involved in mediating the protective effects of preconditioning against IRI.
- Targeting the complement system may offer therapeutic strategies for myocardial IRI.