RECEPTOR-MEDIATED VOLUME REGULATION IN ASTROCYTES IN PRIMARY CULTURE

Changes in astroglial volume were studied after incubating primary cultures from the cerebral cortex of newborn rats for 5 hr in taurine, glutamate or gamma-aminobutyric acid (GABA), alone or together with monoamine receptor agonists. Control cell volume was 2.2-mu-l/mg protein. In the presence of taurine or glutamate there was a small increase in cell volume, further augmented when the cells were incubated in isoproterenol plus taurine or phenylephrine, or isoproterenol plus glutamate. After incubation in 5-hydroxytryptamine (5-HT) plus taurine, on the other hand, the cell volume was not different from the control value. In the presence of GABA, alone or together with adrenoceptor agonists (alpha-1, alpha-2 or beta) or 5-HT, there were no significant changes in cell volume. The regulation of astroglial volume is complicated and affected by ion fluxes, free amino acids and metabolic events including changes in pH. The results are discussed in relation to late data on receptor regulation of active uptake of amino acids. Astroglial volume might be influenced by amino acid transport, partly under control of monoamine receptors.