Intracellular adenosine in isolated rat liver cells

Area of Science:

• Biochemistry
• Cell Biology
• Physiology

Background:

• Adenosine is a crucial signaling molecule.
• Extracellular adenosine levels are often used to infer cellular states.
• The intracellular localization and storage of adenosine remain unclear.

Purpose of the Study:

• To investigate the existence and localization of a non-extracellular adenosine pool in mammalian cells.
• To determine if intracellular adenosine contributes significantly to total tissue adenosine content.

Main Methods:

• Isolation and suspension of rat liver cells using collagenase perfusion.
• Induction of hypoxia to observe changes in adenosine content.
• Treatment with adenosine deaminase to differentiate extracellular and intracellular pools.
• Quantification of residual adenosine levels in isolated cells.

Main Results:

• Hypoxia increased adenosine content in cell suspensions.
• Adenosine deaminase partially reduced adenosine levels but did not eliminate them.
• A significant residual adenosine pool (85 +/- 10 pmol/mg protein) was identified intracellularly.
• This pool was not extracellular, cell-surface bound, or free in the cytoplasm.

Conclusions:

• Mammalian cells, specifically rat liver cells, possess a substantial intracellular adenosine pool.
• This intracellular pool is likely associated with adenine-analog binding proteins.
• Tissue adenosine measurements may not accurately reflect interstitial adenosine concentrations.
• The functional role of this intracellular adenosine pool requires further investigation.