CHARACTERIZATION, LOCALIZATION AND DISTRIBUTION OF alpha 1 ADRENOCEPTOR SUBTYPE IN MALE RABBIT URETHRA

Purpose: The subtype specificity, localization and distribution of urethral alpha1-adrenoceptors were studied in the male rabbit urethra.Materials and Methods: The properties of the urethral alpha1-adrenoceptors were investigated using radioligand receptor binding and light microscopic autoradiography with [(125) I]iodo-2-[b-(4-hydroxyphenyl)-ethylaminomethyl]tetralone (HEAT), and immunohistochemistry with monoclonal anti-alpha smooth muscle actin and anti-alpha sarcomeric actin antibodies.Results: Saturation experiments with [(125) I]HEAT demonstrated the presence of significant amounts of a single high affinity binding site for alpha1 adrenoceptors in the male rabbit urethra. The pharmacological profile of the alpha1 adrenoceptors in rabbit urethra, determined by inhibition experiments with subtype selective alpha1 adrenoceptor antagonists, was characterized by the following rank order of potency of inhibition constants (Ki values): prazosin