Effect of age on oxygen-binding in normal human subjects

Area of Science:

• Physiology
• Biochemistry
• Gerontology

Background:

• Oxygen transport is crucial for cellular respiration and is influenced by various physiological factors.
• Hemoglobin's oxygen affinity is modulated by pH, 2,3-diphosphoglycerate (2,3-DPG), and inorganic phosphate (Pi).
• Age-related changes in blood parameters can impact oxygen delivery and utilization.

Purpose of the Study:

• To investigate the relationship between age and oxygen-binding parameters in healthy non-smokers.
• To determine how plasma and intra-erythrocytic pH influence age-related alterations in hemoglobin-oxygen affinity.

Main Methods:

• Measured oxygen-binding (P50), plasma and intra-erythrocytic pH, hemoglobin, 2,3-DPG, and Pi concentrations in 62 healthy non-smokers (18-89 years).
• Expressed P50 at standard plasma pH (7.40) and PCO2 (5.33 kPa) and at a constant intra-erythrocytic pH (7.20).
• Analyzed correlations between P50, age, and other measured parameters.

Main Results:

• P50 showed a positive correlation with age when expressed at plasma pH 7.40 and PCO2 5.33 kPa.
• This correlation was stronger when P50 was adjusted to a constant intra-erythrocytic pH of 7.20.
• Average P50 at intra-erythrocytic pH 7.20 increased from 3.59 kPa at age 20 to 3.96 kPa at age 90.
• No significant correlation was found between P50 and age for hemoglobin, 2,3-DPG, or Pi concentrations.

Conclusions:

• Hemoglobin-oxygen affinity decreases with age in healthy individuals, particularly when considering intra-erythrocytic pH.
• This age-related shift in oxygen binding may have implications for oxygen delivery to tissues in older adults.
• Factors like hemoglobin concentration and 2,3-DPG do not appear to explain this age-dependent change in P50.