Figure 4.

Effect of inhibiting glutamate transporter on SpH acidification. Comparison of the acidification rates of SpH vesicles at 2 mM ATP when glutamate is present (4 mM; control), when glutamate is absent (0 mM Glu), when VGLUT is blocked by Trypan blue (0.5 μM TB), and in the presence of low (0 mM Cl⁻) or high (10 mM Cl⁻) concentrations of chloride. Acidification rate reduced to ∼90% of control when glutamate was removed but ATP (2 mM) and Cl⁻ (4 mM) were present. When VGLUT was blocked, acidification rate was reduced to ∼70% of control similar to the reduction seen (∼76%) when ATP and glutamate were present but chloride was removed (0 mM Cl⁻). High concentrations of chloride (10 mM Cl⁻) did not reduce the acidification rate. Acidification rate (s⁻¹) for each condition shown above bar. Data analyzed with two-tailed unpaired t-tests against the addition of Trypan blue (0.5 μM TB). ^∗P < 0.0001; ^∗∗P 0.001.