FIGURE 2.

Electrophysiological recordings and the K⁺-selective microelectrodes report similar intracellular K⁺ concentrations. A, scanning electrode image of the K⁺-selective microelectrode before intracellular measurements. B, intracellular K⁺ concentrations in Kv channel-expressing Xenopus oocytes measured with two-electrode voltage-clamp (TEVC) and K⁺-selective microelectrode techniques. Data are expressed as mean values for control oocytes and oocytes injected with 50 nl of indicated test solutions. Error bars show S.E. n = 3–5. C, scanning electron microscope image of the K⁺-selective microelectrode after intracellular measurements.