Summary
The effect of the K+-sparing diuretic amiloride and two of its hydrophobic analogs, methylisobutyl amiloride (MIA) and ethylisopropyl amiloride (EIPA), on Ca-activated K+ channels from renal microvillus membrane vesicles incorporated into planar lipid bilayers was investigated. Amiloride did not inhibit currents through Ca-activated K+ channels. MIA and EIPA, however, inhibited channel currents when added to both the internal and external solutions in concentrations between 10 and 250 μM. Furthermore, when dose-response data for channel inhibition were examined using Hill plots, Hill numbers of ≈ 1.5 were found for both blockers from both sides, suggesting that the mechanism of block involves multiple inhibitory binding sites. A simple kinetic scheme is proposed that can account for the results.
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Zweifach, A., Desir, G.V., Aronson, P.S. et al. Inhibition of Ca-activated K+ channels from renal microvillus membrane vesicles by amiloride analogs. J. Membarin Biol. 128, 115–122 (1992). https://doi.org/10.1007/BF00231884
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DOI: https://doi.org/10.1007/BF00231884