How Hydrogen Ions Help Cells Control Their Size and Shape
- Authors
- Yizeng Li, Xiaohan Zhou, Sean X. Sun
- Journal
- Frontiers in Cell and Developmental Biology
- Year
- 2021
- DOI
- 10.3389/fcell.2021.683686
- Study Type
- clinical
- Peer Reviewed
- Yes
- Country
- United States
- Health Condition
- Osmotic Imbalance Disorders
- Body System
- Cellular
TL;DR
Scientists used computer models to figure out how cells control their size, and they found that hydrogen and bicarbonate ions are way more important than people thought—working together with other ions to keep cells from shrinking or swelling up too much. This matters because understanding how cells stay the right size could help doctors treat diseases where cells grow abnormally or move around where they shouldn't.
Key Finding
Hydrogen ions and bicarbonate play important but previously underappreciated roles in how cells regulate their volume, working alongside better-studied ions like sodium, potassium, and chloride.
Summary
This study used computer models to understand how cells control their size and water content. Researchers focused on the roles of hydrogen ions and bicarbonate (a chemical buffer in cells), along with other ions like sodium and potassium. The models showed that cells maintain stable internal salt concentrations through multiple backup systems involving different ion channels and transporters, and that cells have redundant mechanisms to ensure they don't swell or shrink abnormally.
Practical Takeaway
This is a theoretical computer modeling study with no human testing or hydrogen water administration, so it cannot directly inform whether hydrogen water affects human health or cell function. While the research suggests hydrogen ions are involved in basic cellular processes, the study does not test hydrogen water or any intervention in living organisms.
Abstract
Cells lacking a stiff cell wall, e.g., mammalian cells, must actively regulate their volume to maintain proper cell function. On the time scale that protein production is negligible, water flow in and out of the cell determines the cell volume variation. Water flux follows hydraulic and osmotic gradients; the latter is generated by various ion channels, transporters, and pumps in the cell membrane. Compared to the widely studied roles of sodium, potassium, and chloride in cell volume regulation, the effects of proton and bicarbonate are less understood. In this work, we use mathematical models to analyze how proton and bicarbonate, combined with sodium, potassium, chloride, and buffer species, regulate cell volume upon inhibition of ion channels, transporters, and pumps. The model includes several common, widely expressed ion transporters and focuses on obtaining generic outcomes. Results show that the intracellular osmolarity remains almost constant before and after cell volume change. The steady-state cell volume does not depend on water permeability. In addition, to ensure the stability of cell volume and ion concentrations, cells need to develop redundant mechanisms to maintain homeostasis, i.e., multiple ion channels or transporters are involved in the flux of the same ion species. These results provide insights for molecular mechanisms of cell volume regulation with additional implications for water-driven cell migration.