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Updated: Oct 10, 2026
Model of Ischemia and Reperfusion Injury in Rabbits
Published on: November 3, 2023
Effect of combined K(ATP) channel activation and Na(+)/H(+) exchange inhibition on infarct size in rabbits
1Division of Cardiology, The Heart Institute of Good Samaritan Hospital Los Angeles, California 90017, USA. sharon.hale@attglobal.net
Abstract:
We tested if combining treatment with cariporide, an Na(+)/H(+) exchange inhibitor, and diazoxide, a mitochondrial ATP-sensitive K(+) (K(ATP)) channel opener, would reduce myocardial infarct size (IS) to a greater extent than either intervention alone. Four groups of rabbits were studied (n = 10 each): cariporide (0.3 mg/kg), diazoxide (10 mg/kg), both drugs, and saline control, given 15 min before a 30-min coronary artery occlusion and 3 h reperfusion. IS in controls comprised 47 +/- 6% of the risk region. Cariporide reduced IS by 55% compared with control (21 +/- 3%), but diazoxide did not significantly reduce IS compared with controls (37 +/- 6%). Combined treatment resulted in an IS of 18 +/- 5%. Also we determined that diazoxide did not potentiate a subthreshold dose of cariporide nor did a mitochondrial K(ATP) channel blocker, 5-hydroxydecanoate (5-HD), prevent cariporide from reducing IS. Thus cariporide reduced necrosis by >50% in this model, both in the presence and absence of K(ATP) channel blockade. There was no significant difference in IS reduction between the group receiving cariporide alone and the group receiving combined treatment. Because the effect of cariporide was not blocked by 5-HD, it is unlikely that K(ATP) channels play a role as an end effector in cariporide's mechanism.
Insights
Cariporide significantly reduced myocardial infarct size in rabbits. Combining cariporide with diazoxide did not offer additional protection, suggesting K(ATP) channels are not essential for cariporide
Area of Science:
- Cardiology
- Pharmacology
- Cellular Biology
Background:
- Myocardial infarction (MI) leads to significant heart damage.
- Cardioprotective strategies aim to limit infarct size.
- Investigating novel drug combinations for enhanced protection is crucial.
Purpose of the Study:
- To evaluate the combined effect of cariporide and diazoxide on reducing myocardial infarct size.
- To determine if combining these drugs offers greater protection than monotherapy.
- To elucidate the role of mitochondrial K(ATP) channels in cariporide's mechanism.
Main Methods:
- Rabbit model of myocardial infarction induced by coronary artery occlusion and reperfusion.
- Administration of cariporide (Na(+)/H(+) exchange inhibitor) and diazoxide (K(ATP) channel opener) alone and in combination.
- Assessment of infarct size as a percentage of the risk region.
Main Results:
- Cariporide monotherapy reduced infarct size by 55% compared to controls.
- Diazoxide alone did not significantly reduce infarct size.
- Combined treatment showed no significant improvement in infarct size reduction compared to cariporide alone.
- Cariporide's protective effect was independent of K(ATP) channel blockade.
Conclusions:
- Cariporide is a potent agent for reducing myocardial infarct size.
- Combining cariporide with diazoxide does not enhance cardioprotection in this model.
- Mitochondrial K(ATP) channels are unlikely to be the direct mediators of cariporide's cardioprotective effects.
