Amiloride interacts with [3H]idazoxan and [3H]rauwolscine binding sites in rabbit urethra

Amiloride and its analogues (N-ethylisopropylamiloride and banzamil) interact more potently with [3H]idazoxan binding sites (nM range) than with [3H]rauwolscine binding sites (microM range) in the rabbit urethra. The binding of both radioligands was competitivelly inhibited by amiloride, with increased KD values and no change in their binding capacity. Interestingly, amiloride was a potent inhibitor at [3H]idazoxan binding sites in rabbit urethral smooth muscle at concentrations far below those required to inhibit the Na+/H+ exchanger or electrogenic pump.