Hyperoxia induces alkalinization and dome formation in MDCK epithelial cells

Area of Science:

• Cell Biology
• Physiology
• Biochemistry

Background:

• Confluent Madin-Darby canine kidney (MDCK) cells exhibit dome formation, indicating cell differentiation and transepithelial fluid transport.
• Hyperoxia, or high oxygen levels, is investigated for its effects on epithelial cell function.

Purpose of the Study:

• To investigate the mechanisms by which hyperoxia induces dome formation in MDCK epithelial cells.
• To determine the role of intracellular pH (pHi), extracellular pH (pHo), and cyclic adenosine monophosphate (cAMP) in hyperoxia-induced dome formation (HIDF).

Main Methods:

• Exposure of MDCK cells to varying oxygen concentrations (95% O2, 40% O2, normoxia).
• Measurement of intracellular pH (pHi) and dome formation.
• Inhibition of the Na(+)-H+ exchanger using amiloride.
• Manipulation of extracellular pH (pHo).
• Measurement of adenosine 3',5'-cyclic monophosphate (cAMP) levels.

Main Results:

• Hyperoxia (95% O2) induced significant dome formation in MDCK cells, unlike lower oxygen levels.
• Hyperoxia led to a rise in intracellular pH (pHi) and increased cAMP levels.
• Inhibition of the Na(+)-H+ exchanger reduced dome formation and abolished hyperoxia-induced alkalinization.
• Extracellular pH modulated dome formation, with acidic pH decreasing and alkaline pH increasing HIDF.

Conclusions:

• High-level hyperoxia induces dome formation in MDCK epithelial monolayers.
• This process involves the activation of the Na(+)-H+ exchanger and an increase in intracellular cAMP.
• Changes in intracellular and extracellular pH play critical roles in hyperoxia-induced dome formation.