Ventilation strategy has a major influence on remote ischaemic preconditioning in mice

Area of Science:

• Cardiovascular Research
• Physiology
• Ischaemia-Reperfusion Injury

Background:

• The role of acute oxygen administration during ST-segment elevation myocardial infarction remains controversial.
• The impact of supplementary oxygen on animal models of ischaemia-reperfusion injury and cardioprotection is understudied.

Purpose of the Study:

• To investigate the effect of ventilation with room air versus 100% oxygen on infarct size in a mouse model of myocardial ischaemia-reperfusion.
• To assess the influence of oxygenation on the efficacy of remote ischaemic preconditioning (RIPC) and pharmacological cardioprotection.

Main Methods:

• An in vivo mouse model involving 40 minutes of coronary artery occlusion followed by 2 hours of reperfusion.
• Infarct size measurement using tetrazolium staining and area at risk determination with Evan's blue.
• Evaluation of RIPC and bradykinin-induced pharmacological protection under different ventilation conditions (room air vs. 100% oxygen).

Main Results:

• Ventilation with 100% oxygen significantly reduced infarct size compared to room air (33% vs. 46%).
• Standard RIPC protocols were ineffective in mice ventilated with 100% oxygen.
• Pharmacological protection with bradykinin remained effective even under 100% oxygen ventilation, reducing infarct size.

Conclusions:

• Ventilation protocols significantly influence infarct size in mouse models of myocardial infarction.
• High oxygen ventilation can abolish the protective effects of ischaemic preconditioning protocols.
• These findings have critical implications for the design and interpretation of experimental studies on cardioprotection.