![Figure 6. Voltage dependence of Slo2.1 channel activation is [K+]e dependent. (A) I-V relationships for ISlo2.1 activated with 1 mM NFA in oocytes bathed in an extracellular solution, where [K+]e was varied from 1 to 99 mM. [Na+]e was varied as indicated, so that the sum of [K+]e and [Na+]e was kept constant at 100 mM. Currents were measured from oocytes (n = 5) 3 d after they were injected with 0.84 ng cRNA. (B) Slo2.1 is K+ selective. Reversal potential of ISlo2.1 (Erev) was plotted as a function of log10[K+]e, and the data were fitted by linear regression. The slope of the line is 50.5 mV/decade increment of [K+]e (R2 = 0.99). (C) G-V relationships for Slo2.1 as a function of [K+]e. (D) V1/2 of G-V relationship plotted as a function of log10 [K+]e. The data were fitted with a Hill equation (smooth curve) with an EC50 of 21.2 ± 6.0 mM when the Hill coefficient, nH, was fixed to a value of 1.0 (R2 = 0.99). The data for 300 mM [K+]e was measured in a separate batch of oocytes. (E) I-V relationships for ISlo2.1 activated with 3 mM NFA in oocytes bathed in an extracellular solution, where [K+]e was varied from 1 to 99 mM. [Na+]e was varied as indicated, so that the sum of [K+]e and [Na+]e was kept constant at 100 mM. Currents were measured from oocytes (n = 6) 2 d after they were injected with 0.84 ng cRNA. (F) The slope conductance was determined at the 0 current potential (gErev) of the I-V relationship and plotted as a function of log10[K+]e. The data were fitted with a Hill equation (smooth curve) with an EC50 of 23.5 ± 3.5 mM when the Hill coefficient, nH, was fixed to a value of 1.0 (R2 = 0.99).](https://cdn.rupress.org/rup/content_public/journal/jgp/135/3/10.1085_jgp.200910316/6/jgp_200910316_rgb_fig6.jpeg?Expires=1773573746&Signature=UHyZN6~SaeCToIZe1~tT8c7FVMzt~0mrOTm1grQH7Elrp58jslmJIgaOB6~Kikc4NR5fICwlQvlTMpnboAtqocBX4NAycOydjc4fSx~Rxdq4wikHISmgKiiUQLlVTVexeTivBMld3HmuiFmNz1fdjIW0SFByU3xpACC38aA9CoB1V0JZDPO7pGEhlAceeKvdYCSqh36MD9KVqVFBB1L0FpTDpQ0V9lSB6yyeRinORbmzU5oCm5aqnYR2pYT4C5iC53OhIz2OraBKpUkv7Az~A8DErD-8KK87Arzo9gH7kO72BU0Z8PvuHFVXLcb4hJjzK3o8qiTfTcTnAqSh31OZiQ__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Voltage dependence of Slo2.1 channel activation is [K+]e dependent. (A) I-V relationships for ISlo2.1 activated with 1 mM NFA in oocytes bathed in an extracellular solution, where [K+]e was varied from 1 to 99 mM. [Na+]e was varied as indicated, so that the sum of [K+]e and [Na+]e was kept constant at 100 mM. Currents were measured from oocytes (n = 5) 3 d after they were injected with 0.84 ng cRNA. (B) Slo2.1 is K+ selective. Reversal potential of ISlo2.1 (Erev) was plotted as a function of log10[K+]e, and the data were fitted by linear regression. The slope of the line is 50.5 mV/decade increment of [K+]e (R2 = 0.99). (C) G-V relationships for Slo2.1 as a function of [K+]e. (D) V1/2 of G-V relationship plotted as a function of log10 [K+]e. The data were fitted with a Hill equation (smooth curve) with an EC50 of 21.2 ± 6.0 mM when the Hill coefficient, nH, was fixed to a value of 1.0 (R2 = 0.99). The data for 300 mM [K+]e was measured in a separate batch of oocytes. (E) I-V relationships for ISlo2.1 activated with 3 mM NFA in oocytes bathed in an extracellular solution, where [K+]e was varied from 1 to 99 mM. [Na+]e was varied as indicated, so that the sum of [K+]e and [Na+]e was kept constant at 100 mM. Currents were measured from oocytes (n = 6) 2 d after they were injected with 0.84 ng cRNA. (F) The slope conductance was determined at the 0 current potential (gErev) of the I-V relationship and plotted as a function of log10[K+]e. The data were fitted with a Hill equation (smooth curve) with an EC50 of 23.5 ± 3.5 mM when the Hill coefficient, nH, was fixed to a value of 1.0 (R2 = 0.99).
