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Pharmacological preservation of the ischemic heart
Insights
Nifedipine effectively protected the heart during ischemia by inhibiting calcium influx, significantly reducing myocardial injury. This study highlights a novel approach for myocardial preservation during cardiac procedures.
Area of Science:
- Cardiology
- Pharmacology
- Cell Biology
Background:
- Intracellular calcium accumulation is implicated in ischemic myocardial injury.
- Inhibiting calcium entry into cardiac cells may protect the ischemic heart.
Purpose of the Study:
- To investigate the protective effects of nifedipine, a calcium channel blocker, on myocardial injury during ischemia.
- To evaluate nifedipine's efficacy in preserving heart function during cardiopulmonary bypass.
Main Methods:
- Nifedipine was infused into the aortic root of 6 dogs during 2 hours of myocardial ischemia under cardiopulmonary bypass.
- Control animals (7 dogs) received normal saline at the same flow rate and temperature.
- Cardiac function and myocardial damage were assessed post-reperfusion.
Main Results:
- Control dogs experienced severe left ventricular failure and inadequate hemodynamics after reperfusion.
- Nifedipine-treated dogs were successfully weaned from bypass with minimal support.
- Histological examination revealed less ischemic damage in the nifedipine group compared to controls.
Conclusions:
- Inhibition of transmembrane calcium flux with nifedipine demonstrates a potent cardioprotective effect.
- This approach offers a promising strategy for myocardial preservation during ischemic events.
- Nifedipine represents a potential therapeutic agent for mitigating ischemic myocardial damage.
Abstract:
This study was based on the concept that intracellular accumulation of calcium plays a role in mediating ischemic myocardial injury and that inhibition of entry of calcium into cells may have a salutary effect on the ischemic heart. Nifedipine, a potent vasodilator and inhibitor of transmembrane calcium flux, was infused into the aortic root of 6 dogs (5 microgram/kg/hr) during 2 hours of myocardial ischemia while on cardiopulmonary bypass. Seven control animals received normal saline at the same flow rate and temperature (20 degrees C). The results showed that none of the 7 control animals were able to maintain adequate aortic pressure or cardiac output after 30 to 60 minutes of normothermic reperfusion. All had marked left ventricular failure and were unresponsive to large doses of inotropic agents. In contrast, the 6 dogs treated with nifedipine were weaned from bypass either without difficulty or requiring small doses of calcium chloride and norepinephrine. Light microscopy demonstrated more marked ischemic damage in the control group than in the group of drug-treated dogs. We conclude that the concept of inhibition of transmembrane calcium flux offers a new and potent method for myocardial preservation during ischemia.