Po2 cycling protects diaphragm function during reoxygenation via ROS, Akt, ERK, and mitochondrial channels

Area of Science:

• Physiology
• Cellular Biology
• Biochemistry

Background:

• Skeletal muscle can be damaged by oxygen reintroduction after prolonged low oxygen exposure (hypoxia), a process known as reperfusion injury.
• The protective mechanisms of Po2 cycling (intermittent hypoxia followed by hyperoxia) in skeletal muscle during reoxygenation are not fully understood.

Purpose of the Study:

• To investigate the protective effects of Po2 cycling on skeletal muscle during reoxygenation.
• To elucidate the underlying molecular mechanisms, including the roles of reactive oxygen species (ROS), protein kinase B (Akt), extracellular signal-regulated kinase (ERK), and mitochondrial channels.

Main Methods:

• Real-time detection of ROS production in mouse diaphragmatic skeletal muscle using a dihydrofluorescein fluorescent probe and confocal microscopy.
• Assessment of muscle force generation during reperfusion.
• Inhibition of ROS, Akt, and ERK signaling pathways, and modulation of mitochondrial channels (KATP and mPTP) to evaluate their role in Po2 cycling's protective effects.

Main Results:

• Po2 cycling significantly attenuated ROS levels in diaphragmatic muscle.
• Muscles treated with Po2 cycling demonstrated enhanced force generation during reperfusion compared to controls.
• Inhibitors and stimulators targeting ROS, Akt, ERK, KATP, and mPTP abolished the functional improvements observed with Po2 cycling.

Conclusions:

• Po2 cycling confers protection against reperfusion injury in diaphragmatic skeletal muscle.
• A signaling pathway involving ROS, Akt, ERK, and mitochondrial channels (KATP and mPTP) mediates the protective effects of Po2 cycling during reoxygenation.