Abstract
The interaction of amiloride and amiloride derivatives with the Na + channels of pig kidney membranes was studied from 22Na + uptake experiments. The order of potency of the different molecules tested is: phenamil > benzamil > amiloride, ethylisopropylamiloride. [ 3H]labelled phenamil was prepared and used to titrate Na + channels in pig kidney membranes. Kinetics experiments, equilibrium binding studies and competition experiments between [ 3H]phenamil and unlabelled phenamil indicate that phenamil recognizes a single family of binding sites with a K d value of 20 nM and a maximum binding capacity of 11.5 pmol/mg of protein. The order of potency of different amiloride analogs tested in [ 3H]phenamil competition experiments is identical to that found for the inhibition of 22Na + uptake by apical Na + channels.
Published Version
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