ACTA ENDOCRINOLOGICA (BUC)

Developments in the understanding of the molecular basis of water permeability of the red blood cell (RBC) have taken place rapidly since the discovery in 1985 in Cluj- Napoca, Romania, by the group of Benga of a water channel protein (WCP), later called aquaporin 1 (AQP1), in the RBC membrane. However, the physiological role of AQP1 is not yet fully understood. Investigations of RBCs from human subjects of various ages could help shed light on this important issue. We present a short review of our studies on this topic that were published in less “visible” journals and books. The diffusional water permeability (Pd) of the RBC membrane has the lowest values in the newborns. Then Pd values are increasing in children, reaching at about 7 years a value that remains rather constant in young and mature subjects. The high permeability to water of the RBC membrane can be correlated at these ages with the ability to undertake a high level of physical activity. In elderly individuals (over 65 years) a further small, but statistically significant, increase in the diffusional water permeability of RBC was observed. In this case the higher RBC water permeability can be correlated with a requirement of the RBC membrane to favour the membrane undulations and the rapid entry or exit of solutes of molecular size greater than water, in conditions when the organism is less physically active, probably has lower metabolic rates and lower mean rates of blood circulation.