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Preconditioning reduces tissue complement gene expression in the rabbit isolated heart.
E J Tanhehco1, K Yasojima, P L McGeer
1University of Michigan Medical School, Department of Pharmacology, Ann Arbor, Michigan 48109, USA.
The American Journal of Physiology
|December 22, 1999
Summary
Preconditioning reduces complement proteins in the heart, potentially protecting against ischemia-reperfusion injury. This protective effect involves the ATP-dependent K+ (KATP) channel and lowers key complement components like C3.
Area of Science:
- Cardiovascular Science
- Immunology
- Molecular Biology
Background:
- Myocardial ischemia-reperfusion injury is a significant clinical concern.
- Complement activation contributes to this injury.
- Preconditioning strategies can mitigate myocardial damage.
Purpose of the Study:
- To investigate the effect of preconditioning on complement expression in isolated rabbit hearts.
- To determine if preconditioning reduces local complement component production.
Main Methods:
- Rabbit hearts underwent ischemic or chemical preconditioning (pinacidil).
- Complement component mRNA levels (C1q, C1r, C3, C8, C9) were measured.
- Protein expression of C3 and membrane attack complex was assessed via Western blot and immunohistochemistry.
- The role of ATP-dependent K+ (KATP) channels was evaluated using glyburide.
Main Results:
- Both ischemic and chemical preconditioning significantly reduced mRNA levels of C1q, C1r, C3, C8, and C9.
- A similar reduction in C3 and membrane attack complex protein expression was observed.
- The KATP channel blocker glyburide reversed these reductions in mRNA expression.
Conclusions:
- Preconditioning, both ischemic and chemical, decreases the expression of key complement components in the myocardium.
- This reduction in local complement production may be a crucial mechanism underlying preconditioning's protective effects against ischemia-reperfusion injury.
- The ATP-dependent K+ (KATP) channel plays a role in mediating these effects.