Intracellular chloride activity in cultured mesangial cells

Glomerular mesangial cells require Cl ions for the development of a variety of metabolic and functional properties. In the present study the electrochemical distribution for Cl- was examined in cultured rat mesangial cells with Cl(-)-sensitive intracellular microelectrodes. It was determined that the intracellular Cl activity exceeded the levels predicted for a passively distributed ion. This was further substantiated by exposing mesangial cells to 10(-5) M bumetanide which drove intracellular Cl to a value close to electrochemical equilibrium. We conclude that Cl accumulates in mesangial cells, against its electrochemical gradient, through a transport pathway that is highly sensitive to bumetanide.