The entrapment of [14C]ascorbic acid in human erythrocytes

Area of Science:

• Biochemistry
• Cell Biology
• Human Physiology

Background:

• Ascorbic acid, also known as vitamin C, is an essential nutrient.
• Understanding the cellular uptake mechanisms of ascorbic acid is crucial for human health.
• Red blood cells play a vital role in oxygen transport and maintaining cellular integrity.

Purpose of the Study:

• To investigate the mechanism of ascorbic acid and dehydroascorbic acid transport into human red blood cells.
• To identify the form of ascorbic acid that enters and is retained within red blood cells.
• To elucidate the cellular processes involved in ascorbic acid entrapment.

Main Methods:

• Incubation of radioactively labeled ascorbic acid and dehydroascorbic acid with human blood.
• Isolation and characterization of intracellular moieties using infrared spectroscopy.
• Analysis of ascorbic acid entrapment influenced by incubation time, temperature, and specific inhibitors.

Main Results:

• Ascorbic acid and dehydroascorbic acid irreversibly migrate into human red blood cells.
• Infrared spectroscopy confirmed the intracellular form as L-ascorbic acid.
• Entrapment is dependent on incubation time and temperature, and sensitive to inhibitors of anion transport and active transport.

Conclusions:

• Ascorbic acid is oxidized to dehydroascorbic acid on or near the red blood cell surface.
• Dehydroascorbic acid crosses the cell membrane and is reduced back to ascorbic acid intracellularly.
• The inability of the reduced L-ascorbic acid to exit the cell leads to its entrapment, establishing a vitamin C reservoir.