PHARMACOLOGICAL STUDIES WITH DERIVATIVES OF 2-AMINOTETRALIN, BENZHYDRO[F]QUINOLINE AND CLONIDINE SUGGEST A PHARMACOLOGICAL IDENTITY BETWEEN PERIPHERAL AND CENTRAL ALPHA-2 ADRENOCEPTORS .1.

  • 1 January 1983
    • journal article
    • research article
    • Vol. 224  (2) , 346-351
Abstract
A series of hydroxy 2-aminotetralins, benzhydro[f]quinolines and clonidine were used to determine whether a pharmacological similarity could be demonstrated between presynaptic .alpha.-adrenoceptors which modulate autonomic transmission in the guinea pig. Compounds were assayed on isolated field stimulated guinea-pig ilea (GPI) to determine their inhibitory activities on cholinergic transmission. Inhibition of noradrenergic transmission was determined by assaying compounds on isolated field stimulated guinea-pig atria. 2-Aminotetralins, benzhydro[f]quinolines, and clonidine impaired cholinergic and noradrenergic transmission by interacting with presynaptic .alpha.2 adrenoceptors. A correlation (r = 0.95; P < 0.05) was demonstrated between the activity of a compound on the GPI and guinea pig atria. IC50 [median inhibitory concentration] values obtained on GPI were correlated with previously reported IC50 values obtained for binding [3H]clonidine sites in homogenates of calf frontal cortex. A significant correlation was demonstrated (r = 0.99; P < 0.05). .alpha.2-Adrenoceptors localized on guinea pig atria and GPI evidently are pharmacologically similar. A similar structure activity relationship was demonstrated for presynaptic .alpha.2 adrenoceptors on GPI and binding sites labeled by [3H]clonidine in the calf frontal cortex.

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