Fig. 1

NG2-glia express potassium channel subtype Kir4.1 throughout mouse brain development. a The cartoon in the upper panel illustrates the approach for sorting tdTomato fluorescently labeled NG2 cells from NG2DsRedBAC transgenic mouse brain using the FACS method. Lower panel shows the brain cells harvested from postnatal 2-week-old NG2DsRedBAC mouse before and after sorting by FACS. Red fluorescently labeled cells are sorted NG2+ cells for sequential PCR and Western blot tests. b Representative PCR and Western blots showing Kir4.1 mRNA and protein expression in purified NG2-glia from NG2DsRedBAC transgenic mouse brain at postnatal 2 weeks. c The heat map shows a secondary enrichment gene kcnj10 (Kir4.1) among inwardly rectifying K⁺ channel genes family expressed in NG2-glia in a PDGFRα-creER; Rosa26-mGFP transgenic mouse brain at postnatal 7 weeks. d The cartoon and single-cell RT-PCR results illustrate single patched NG2-glia in PDGFRα-creERT; Rosa26-mGFP transgenic mouse hippocampus at postnatal 6–8 weeks. It clearly shows Kir4.1 expression in adult NG2-glia with GFP fluorescence identification. e Representative traces show macroscopic currents (A), macroscopic currents after bath application of Ba²⁺ (B), and Ba²⁺-sensitive currents (C) in a whole-cell patched NG2-glia in PDGFRα-mGFP transgenic mouse hippocampus at postnatal 8 weeks. n = 9 cells. f Representative traces showed the same as in (e) but for NG2-glia with Kir4.1 deletion from PDGFRα-mGFP; Kir4.1^−/− transgenic mouse at postnatal 8 weeks. n = 12 cells. g Average I/V plots showed a dramatic downregulation of inwardly rectifying current in NG2-glia from PDGFRα-mGFP; Kir4.1^−/− transgenic mice compared with its wild-type control. The error bars represent s.e.m. Statistical significance was assessed as indicated using two-tailed unpaired t-test. h The upper graph shows Kir4.1 currents in NG2-glia comprise a large portion of total inward K⁺ channel currents at a holding voltage of −140, −130, −120, −110, and −100 mV, respectively. The lower graph illustrates that more than 90% of Kir4.1 currents in NG2-glia are blocked by 100 µM Ba²⁺, which indicates a high efficiency of 100 µM Ba²⁺ pharmacological blockade for Kir4.1