Rationale: Figure 2A: Paired recordings between synaptically connected cartwheel cells in the presence of GABA receptor antagonists SR95531 allow detecting glycinergic neurotransmission specifically, measuring IPSC. Glycinergic neurotransmission is acutely reduced when presynaptic surface glycine reuptake by GLYT2 is inhibited pharmacologically (ORG25543). IPSC amplitudes ran down soon after drug application (Fig. 2A), declining to 59 ± 11% of baseline within 10–11 min and 3 ± 1% of baseline within 30 min of drug application. Figure 2E: adding exogenous glycine to the whole-cell internal solution in the presynaptic cell occluded the rundown caused by GlyT2 block, showing that the ORG25543 effect was specifically due to loss of glycine availability in the presynaptic terminal. These results show that GLYT2 constitutively supplies glycine for refilling recycling vesicles.. Experimental description: "Wild-type mice of either sex (C57BL/6 or CBA) postnatal 15–24 d were used for the majority of the experiments."