THE CATECHOLAMINE CARRIER OF BOVINE CHROMAFFIN GRANULES - FORM OF THE BOUND AMINE

  • 1 January 1983
    • journal article
    • research article
    • Vol. 23  (2) , 431-436
Abstract
The binding of [2-3H]dihydrotetrabenazine (2-hydroxy-3-isobutyl-9,10-dimethoxy-1,2,3-4,6,7-hexahydro-11bH-benzo [.alpha.]quinolizine), a tetrabenazine derivative which binds to the catecholamine carrier of chromaffin granule membranes, was studied as a function of the pH. The number of binding sites was constant from pH 6.5 to 9.0, while the Kd decreased to a minimal plateau value, obtained at pH values higher than 7.5, the drug pKa. The pH dependency of the displacement of [3H]dihydrotetradbenazine by noradrenaline [norepinephrine] was also investigated. Noradrenaline Kd values derived from displacement experiments decreased logarithmically when the pH increased from 6.5 to 8.5, i.e., for pH values lower than the pKa of noradrenaline. These pharmacological data support the previous hypothesis based on kinetic data that the monoamine carrier of the chromaffin granule membrane binds and transports neutral amines, a form of low abundancy at physiological pH but for which it has a high affinity.

This publication has 0 references indexed in Scilit: