[3H]clonidine binds at multiple high affinity states in human prefrontal cortex.
[3H]Clonidine binds at particulate membrane fractions of human prefrontal cortex in a process that demonstrates high affinity, saturability, reversibility, alpha 2-adrenergic selectivity and the existence of multiple affinity states. At 37 degrees C maximal specific [3H]clonidine binding was briefly attained at 10 and lasted only until 15 min, while at 21 degrees C maximal binding was maintained from 20 to 90 min. At 21 degrees C, rate dissociation studies and saturation analyses were at least biphasic, and adrenergic competitors decreased [3H]clonidine binding with Hill coefficients less than 0.70. Analysis of these data showed at least two affinity states with apparent KDs of 0.34 and 6.0 nM, and the order in which ligands decreased [3H]clonidine binding was clonidine greater than (-)-epinephrine greater than (-)-norepinephrine greater than yohimbine greater than (+)-norepinephrine greater than (+/-)-isoproterenol greater than prazosin greater than serotonin.
M A
MA
Carlson
A C
AC
Andorn
D000328:Adult; D001667:Binding, Competitive; D002540:Cerebral Cortex / Q000378:metabolism*; D003000:Clonidine / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008875:Middle Aged; D013696:Temperature
D003000:Clonidine