Fig. 4.
Cl− accumulation by bumetanide- and Na+-sensitive mechanism in injured neurons.A, Top traces, In the presence of 10−5m bumetanide, the amplitude of inward current response to 10−5m GABA gradually decreased in injured neurons. After the end of bumetanide, inward GABA response gradually restored (top current traces). Disruption of current trace during each GABA application is attributable to rapid current response to voltage ramp to measure theEGABA-A. GABA was applied at an interval of 10 min. Vh was −50mV.Bottom graph, In this neuron, a reversible disturbance of Cl− accumulation by 10−5mbumetanide was demonstrated. Axotomy was performed 2 d before making preparation. B, Decreases of [Cl−]i resulted from disturbance of Cl− accumulation by 10−5m bumetanide in the control (cont.; n = 5) and injured (inj.; n = 5) neurons and by a removal of extracellular Na+ in injured neurons (n = 4).