Sevoflurane before or after ischemia improves contractile and metabolic function while reducing myoplasmic Ca(2+)...

Area of Science:

• Cardiology
• Anesthesiology
• Cardiovascular Physiology

Background:

• Myocardial reperfusion injury involves detrimental calcium (Ca2+) loading.
• Volatile anesthetics, like sevoflurane, are known to mitigate reperfusion injury.
• Investigating the timing of sevoflurane administration is crucial for optimizing its protective effects.

Purpose of the Study:

• To determine if sevoflurane administered before ischemia reduces myoplasmic calcium levels and improves cardiac function more effectively than when given during reperfusion.
• To compare the cardioprotective effects of sevoflurane given pre-ischemia, post-ischemia, or both.

Main Methods:

• Isolated guinea pig hearts were subjected to global ischemia followed by reperfusion.
• Four groups were studied: control, sevoflurane before ischemia (SBI), sevoflurane after ischemia (SAI), and sevoflurane before and after ischemia (SBAI).
• Myoplasmic calcium transients and cardiac function were monitored using the fluorescent probe indo-1.

Main Results:

• Sevoflurane administration (SBI, SAI, SBAI) attenuated the rise in myoplasmic calcium during reperfusion and improved cardiac contractility, relaxation, and efficiency compared to controls.
• SBI demonstrated greater protective effects than SAI in improving cardiac function and reducing calcium loading.
• SBAI generally offered more protection than SAI, indicating a benefit from both pre- and post-ischemic exposure.

Conclusions:

• Sevoflurane administration, particularly before ischemia, effectively reduces calcium loading and enhances post-ischemic cardiac function.
• Pre-ischemic sevoflurane provides superior cardioprotection against reperfusion injury compared to post-ischemic administration.
• The anesthetic's protective effect is likely mediated by reduced calcium overload during reperfusion.