ACTA ENDOCRINOLOGICA (BUC)

Aim. To compare the red blood cell (RBC) diffusional water permeability (Pd) in elderly human subjects and mature\r\nsubjects.\r\nPatients and methods. 58 apparently healthy subjects, aged 65-80 years, were divided into two groups: 44 mature (35-64.9 years) and 14 elderly subjects (65-80 years). The morphological characteristics of RBCs were determined from light microscopic measurements and their Pd was measured\r\nby a NMR method. The inhibition of Pd induced by p-chloromercuribenzoate (PCMB) and the activation energy (Ea,d) of water diffusion across the RBC membrane\r\nwere also determined.\r\nResults. No significant differences between the RBCs of the two groups were found in regard with morphological parameters. Pd (10-3 cm/s) was in case of mature subjects ~ 3.1 at 15?C, 3.6 at 20?C, 4.2 at 25?C, 5.0? at 30?C, 6.1 at 37?C and 7.3 at 42?C, while for elderly subjects Pd was ~ 3.4 at 15?C, 3.9 at 20?C, 4.5 at 25?C, 5.3 at 30?C, 6.6 at 37?C and 7.9 at 42?C. Although rather small these differences were statistically significant: p<0.004 to p <0.04 at various temperatures. This means that RBCs from\r\nelderly people have a higher Pd. In agreement with this suggestion, the values of inhibition of water permeability induced by PCMB were higher for the RBCs from elderly individuals; however, the differences were not statistically significant. Ea,d was the same (~23 kJ/mol) for the RBCs from both groups. After incubation with PCMB Ea,d was ~ 37 kJ/mol for the mature individuals and ~ 31 kJ/mol for\r\nelderly individuals; however, the differences were not statistically significant.\r\nConclusion. A small, but statistically significant, increase in Pd of RBCs from elderly individuals was observed. This can be correlated with peculiarities of a less physically active organism.