Hypoosmotic volume regulation and osmolyte transport in astrocytes is blocked by an anion transport inhibitor, L-644,711

Abstract

Cell volume, potassium content, and potassium influx were measured in rat cerebral astrocytes grown in primary culture following exposure to hypoosmotic medium containing either 3.2 mM or 50 mM potassium. Some solutions also contained 1 mM L-644,711, an anion transport inhibitor. L-644,711 inhibited volume regulation and taurine efflux induced by hypoosmotic exposure in medium containing either potassium concentration. L-644,711 also inhibited potassium uptake associated and not associated with the sodium/potassium pump. The correlation of reduced taurine efflux and volume decrease produced by L-644,711 exposure indicates the important role for this amino acid in hypoosmotic astrocyte volume regulation. However, the effects of L-644,711 on potassium transport indicate that multiple actions of this drug may be important factors in its effect on astrocyte volume regulatory mechanisms.