Ions and water transmembrane transport in nervous and testicular cultured cells in low gravity conditions

Aim of the present study was to investigate on the possible alterations induced by on ground modeled microgravity on ion-water transport proteins at cellular level For the purpose we used astrocytes, C₆ line, neurons (NT₂ line from human teratocarcinoma) and testicular cells (germ cells, Sertoli cells, and Leydig cells; primary cultures from trypsinised prepuberal pig testes). Modeled microgravity was achieved by a desktop 3D Random Positioning Machine, cultures were kept rotating for 30', Ih and 24h. After 30', immunopositivity for the antibodies to Na⁺/K⁺ATPase and Na⁺/K⁺/Cl^- co-transporters was greatly diminished, the plasma membrane appeared to be altered, and the mitochondria inner cristae were disrupted. Immunostaining to the antibody to the water channel aquaporin 4 was very bright. After 1h at random rotation immunostaining for the heat shock protein Hsp27 was visible, After 24h, immunostaining for the ion transport proteins was again like that of the controls, plasma membrane and the mitochondria were again normal. Immunostaining for aquaporin 4 become again similar to that of the controls. We conclude that low gravity induces only transient alterations in the cell's transmembrane ion-water transport: the cells are able to adapt to the gravity vector changes in few hours.