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. 1999 Mar 15;515(Pt 3):639–651. doi: 10.1111/j.1469-7793.1999.639ab.x

Figure 6. Ba2+ inhibition of inward rectifier potassium currents in Xenopus oocytes injected with RNA encoding Kir2.1 cloned from vascular smooth muscle cells.

Figure 6

Membrane current recorded from the same oocyte with voltage steps from a holding potential of −10 mV to −60 mV in the presence of 0 (control), 10 and 100 μM Ba2+. External K+ was 90 mM. Dotted line indicates zero current level. B, current-voltage relationship demonstrating the effect of applying 0.3, 1, 3, 10, 30 and 100 μM Ba2+ on membrane currents recorded at the end of 10 s voltage pulses (n = 5). Bathing K+ was 90 mM. C, relationship between external Ba2+ concentration and the fractional inhibition of inward current at −20, −40, −60, −80 and −100 mV. Data were fitted with eqn (1), to give Kd values of (μm): 21.4, 7.2, 3.5, 1.6 and 0.8 at −20, −40, −60, −80 and −100 mV, respectively. D, voltage dependence of the dissociation constants (Kd) from C. Data were fitted with eqn (2) with a Kd at 0 mV of 41.7 μM, and a slope (μ) of 0.51.

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