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Dense (aged) circulating red cells contain normal concentrations of adenosine triphosphate (ATP)
Insights
Red blood cells (RBCs) lose adenosine triphosphate (ATP) as they age. However, this study found that the ATP concentration in dense, older RBCs remained stable, suggesting ATP loss isn't why old cells are removed.
Area of Science:
- Hematology
- Cellular Biology
- Biochemistry
Background:
- Red blood cells (RBCs) have a finite lifespan and are removed from circulation as they senesce.
- Adenosine triphosphate (ATP) is crucial for maintaining RBC function and integrity.
- Previous hypotheses suggested that a decline in cellular ATP contributes to RBC removal.
Purpose of the Study:
- To investigate the relationship between ATP content and the removal of senescent red blood cells.
- To determine if reduced ATP concentration is a causative factor in the clearance of aged RBCs.
Main Methods:
- Separation of the densest 0.1%--1% of circulating RBCs, representing older cells.
- Determination of ATP content in these dense cells compared to unfractionated controls.
- Analysis of cell size and ATP concentration in dense vs. control RBC populations.
Main Results:
- The densest (oldest) RBCs exhibited lower total ATP amounts compared to unfractionated cells.
- These dense cells were also smaller in size.
- The concentration of ATP within the dense cells was comparable to that of control cells.
Conclusions:
- Despite lower total ATP, the ATP concentration per cell in dense, aged RBCs is similar to controls.
- Reduced cellular ATP is unlikely to be the primary driver for the removal of senescent red blood cells from circulation.
- This finding challenges the hypothesis that ATP depletion causes RBC senescence and clearance.
Abstract:
The densest 0.1%--1% of circulating red cells were separated from fresh blood, and the ATP content of a representative sample of such cells was determined. The dense ("old") cells had decreased amounts of ATP relative to unfractionated cells. However, the dense cells were also smaller, and the concentration of ATP in these cells was the same as in controls. Therefore, it seems unlikely that loss of cellular ATP is a causative factor in removal of senescent red cells from the circulation.