Table 1.

Endogenous Kv2.1 channel number in rat hippocampal neurons based on immunofluorescence and electrophysiology

	DIV 14	DIV 20
Current IkDR @ +40mV (pA)	10,890 ± 1,224 (n = 20)	16,308 ± 1,761 (n = 10)#
Conducting Kv2.1 channels	12,965 ± 1,457 (n = 20)	19,414 ± 2,096 (n = 10)#
Surface area (μm2)	5,200 ± 250 (n = 20)	5,665 ± 714 (n = 10)
Clustered channels	48,313 ± 4,847 (n = 18)*	50,712 ± 4,122 (n = 18) *
Non-clustered channels	50,265 ± 6,469 (n = 18)*	33,059 ± 5,058 (n = 18)*#
Total channels	96,578 ± 11,317 (n = 18)*	85,891 ± 8,815 (n = 18)*
Conducting channel density (no./pF)	228 ± 27 (n = 20)	361 ± 67 (n = 10)
Clustered channel density (no./pF)	819 ± 104 (n = 18)*	813 ± 63. (n = 18)*
Nonclustered channel density (no./pF)	889 ± 114 (n = 18)*	519 ± 69 (n = 18)#
Total channel density (no./pF)	1709 ± 200 (n = 18)*	1360 ± 125 (n = 18)*

Kv2.1 immunofluorescence was measured in cells fixed and immunolabeled using a C-terminal Kv2.1 primary antibody (K99/14, NeuroMab) and a Alexa Fluor 594-conjugated secondary antibody (Invitrogen). Alexa Fluor 594 fluorescence was converted to channel density using immunolabeled GFP-Kv2.1 expressing HEK cells as a standard. Whole-cell electrophysiology was used to measure the delayed rectifier current, Ik_DR, 125 ms after step depolarizations to + 40 mV. Sixty percent of the Ik_DR was attributed to Kv2.1, and this was converted to channel number using the single-channel conductance. Channel density was calculated by dividing channel number by the average whole-cell capacitance, C_M. Neuronal surface area was derived from whole cell capacitance (*p < 0.05 compared to conducting Kv2.1;

^#p < 0.05 compared to DIV 14).