Glutamate transporters of blood platelets as potential peripheral markers to analyze changes of glutamate transport activity in brain under altered gravity conditions.

Activity of high-affinity glutamate transporters was altered in brain nerve terminals under artificial gravity conditions. Blood platelets contain glutamate transporters and are able to uptake glutamate. The goal of the research was to analyze comparatively L-[14C]glutamate transport in neuronal and non-neuronal tissues. The kinetic characteristics of transporters, [Na+]-dependence and influence of competitive transporter inhibitor DL-threo-beta-hydroxyaspartate (DL-THA) on the glutamate uptake by synaptosomes and platelets were determined. Km value of the L-[14C]glutamate uptake was very similar for preparations. Controversy, Vmax was three orders lower for platelets as compared with synaptosomes. It seems to correlate with reduced number of glutamate transporters in the plasma membrane of platelets in comparison with nerve terminals. It was concluded that the glutamate uptake process was primarily similar for both objects studied. Thus, it is reasonable to use platelets as potential peripheral diagnostic markers to analyze changes of glutamate transport activity in brain under altered gravity conditions.