Figure 1.

Nonselective cation channel of hST. (a) Single channel currents in asymmetrical KCl (150/15 mM). Tracings were filtered at 50 Hz to show the unitary conductance in the absence of subconductance states. Holding potentials are indicated on the right. (b) Current-to-voltage (I/V) relationship in asymmetrical KCl (n = 10) was fitted with the Goldman-Hodgkin-Katz (GHK) equation (solid line). (c) Multiple conductance substates (Top) were identified as mean vs. variance plots (Middle), and low variance histograms (Bottom). (d) Single channel currents in symmetrical KCl (150 mM). (e) I/V relationships in KCl (filled circles, n = 6), Na⁺/K⁺ (open triangles, n = 6) and K⁺/Ca²⁺ (open circles, n = 3). (f) Single channel currents in K⁺/Na⁺ (n = 6), and K⁺/Ca²⁺ (g, n = 3). (h) Inhibition of (cis) K⁺ currents by addition of Ca²⁺ in trans (n = 3).