CORRELATION BETWEEN HUMAN PLATELET CYTOPLASMIC MEMBRANE OUTER LEAFLETFLUIDITY, NA+ H+ EXCHANGER ACTIVITY AND AGING/

A cross-sectional survey was undertaken to study the aging effect on p latelet cytoplasmic membrane outer leaflet fluidity and Na+/H+ antipor ter activity, and to investigate the relative influence of membrane or der and age on the Na+/H+ exchanger. The study population consisted of 19 healthy subjects (age range 22-83 years, mean age 48.5 +/- 16.5 ye ars; 12 females and 7 males). Washed platelets were used as neuronal m odels and as eventually contributing to brain pathology by aberrant se cretion of their granule content. A significant positive correlation ( r = 0.48, p < 0.05) was found between age and the membrane structural order, according to a second-degree equation. Sewall-Wright path coeff icient analysis revealed that the age influence on Na+/H+ exchanger ac tivity was unimportant (0.18), but those of cytoplasmic membrane outer leaflet fluidity and mean platelet volume were strong and positive (0 .51 and 0.54, respectively). Women presented a marked standard deviati on in the countertransporter results. In conclusion, decreased membran e outer leaflet fluidity and unchanged Na+/H+ antiporter activity may contribute to the process of normal blain aging.