FIG. 5.

Storage and secretion of GABA by insulin-containing LDCVs in human β-cells. A: GABA release was detected by patch-clamping in an identified β-cell overexpressing α₁/β₁ GABA_AR (upper trace). The cell was held at −70 mV and infused with intracellular solution containing 2 μmol/l free Ca²⁺. Serotonin release was measured simultaneously in the same cell by carbon fiber amperometry (lower trace). The dashed lines indicate simultaneous occurrence of GABA-induced TICs and amperometric currents. B: Immunogold labeling of GABA in a human β-cell. Scale bar: 250 nm.