Type I cell ROS kinetics under hypoxia in the intact mouse carotid body ex vivo: a FRET-based study

Area of Science:

• Physiology
• Cell Biology
• Neuroscience

Background:

• Reactive oxygen species (ROS) play a role in the carotid body's (CB) oxygen-sensing mechanism.
• NADPH oxidases are a primary source of ROS involved in this cascade.

Purpose of the Study:

• To investigate the kinetics of ROS in mouse CB type I cells during hypoxia.
• To determine the role of NADPH oxidase in hypoxia-induced ROS changes and membrane potential (MP) depolarization.

Main Methods:

• Mouse CB type I cells were transfected with the ROS sensor FRET-HSP33.
• Immunohistochemistry confirmed FRET-HSP33 expression.
• ROS levels and MP were measured ex vivo under hypoxic conditions.
• The effect of 4-(2-aminoethyl)benzensulfonylfluorid (AEBSF), an NADPH oxidase inhibitor, was assessed.

Main Results:

• Hypoxia caused a reversible decrease in ROS in one group of CBs, inhibited by AEBSF, suggesting NADPH oxidase involvement.
• Hypoxia caused a reversible increase in ROS in another group of CBs, slightly enhanced by AEBSF.
• Both ROS changes occurred alongside hypoxia-induced MP depolarization, which was inhibited by AEBSF.
• ROS and MP changes correlated with decreased CB tissue oxygen levels.

Conclusions:

• Attenuated p47(phox) subunit activity of NADPH oxidase under hypoxia likely triggers type I cell MP depolarization via ROS decrease.
• Increased ROS observed under certain hypoxic conditions does not influence type I cell MP kinetics.