Epithelial Sodium Channels: Ligand Binding Techniques in Intact Tissues and Homogenates
Sodium channels occur in the apical membranes of various epithelial cells, and are blocked by the pyrazine diuretic, amiloride. Using its N-benzyl derivative (labeled), [3H]benzamil, the choice of which is considered, binding studies have been performed under optimized conditions with intact epithelia and with homogenates. Related work, by current fluctuation analysis has been done elsewhere. Data are presented from experiments with frog skin epithelium, the avian coprodaeum, and rat kidney. The binding sites detected in the first two tissues have properties consistent with apical sodium channels, while those in kidney may be related to non-electrogenic sodium-proton exchange. Emphasis is placed throughout on physiological manipulations which affect both function and binding, and on the wide discrepancies in the amount of binding found in intact and homogenized tissues.
KeywordsSodium Channel Sodium Transport Short Circuit Current Intact Tissue Frog Skin
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