Atypical [(3)H]clonidine binding sites in human caudate and platelets on cryostat-cut sections.
Pharmacological characterization is described for a human imidazoline binding site (I-site) labeled by [(3)H]clonidine using standard autoradiographic method. Under conditions that mask alpha(2)-adrenergic sites, only a single high affinity site was observed in human caudate and blood platelet sections. Affinity constants (K(i)) were highly correlated between the two tissues (r = 0.90, P = 0.0003). This site is dissimilar to classical I(1) and I(2) sites, even though both tissues possess abundant I(1) and I(2) sites by filtration binding methods. It is suggested that the isotonic buffer conditions inherent to the procedure alter drug affinities to the classical I(1) site.
Zhu
H
H
University of Mississippi Medical Center, Jackson, Mississippi 39216, USA. hzhu@psychiatry.umsmed.edu
Halaris
A
A
Piletz
J E
JE
D000316:Adrenergic alpha-Agonists / Q000378:metabolism*; D000317:Adrenergic alpha-Antagonists / Q000378:metabolism; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001665:Binding Sites; D001792:Blood Platelets / Q000737:chemistry / Q000378:metabolism*; D001923:Brain Chemistry; D002421:Caudate Nucleus / Q000737:chemistry / Q000378:metabolism*; D003000:Clonidine / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D006247:Harmine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007093:Imidazoles / Q000737:chemistry / Q000378:metabolism; D054755:Imidazoline Receptors; D008297:Male; D008875:Middle Aged; D011869:Radioligand Assay; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism; D011955:Receptors, Drug / Q000378:metabolism
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D007093:Imidazoles; D054755:Imidazoline Receptors; D018341:Receptors, Adrenergic, alpha-2; D011955:Receptors, Drug; D006247:Harmine; C005010:harman; D003000:Clonidine; C014282:cirazoline