A new amiloride analogue, "amiloride-caproic acid," was synthesized, coupled to albumin, and used as a hapten to raise anti-amiloride antibodies in rabbits. The antibodies were affinity purified with an amiloride affinity column and characterized. Binding studies using [3H]benzamil showed a dissociation constant of 0.8 nM. Amiloride and amiloride-caproate inhibited [3H]benzamil binding; epsilon-guanidinocaproic acid showed no inhibition. Anti-amiloride antibodies reversed the inhibition by amiloride of sodium transport across toad urinary bladder. Anti-amiloride antibodies and an amiloride affinity column should provide useful tools for the characterization of the epithelial sodium channel.
