Complex interaction of alpha(2)-adrenoceptor binding sites with bovine brain and lung extracts containing clonidine-displacing substance.
Previous studies have established that methanolic extracts of bovine brain and lung possess CDS activity with an agonist-like profile at alpha(2)-adrenoceptor binding sites (i.e., greater potency against [(3)H]-clonidine sites than against [(3)H]-RX-821001 sites). Following prolonged reflux in ethylacetate, monovalent cations and histamine were removed from the lung extract, and the resulting extract exhibited similar potency against both radioligands, indicative of an antagonist-like profile. These observations help explain the absence of biologic activity at alpha(2)-adrenoceptors in the methanolic extracts as reported in our companion paper.
Pinthong
D
D
School of Biomedical Sciences, The Medical School, Queen's Medical Centre, Clifton Boulevard, Nottingham NG7 2UH, UK.
Kendall
D A
DA
Wilson
V G
VG
D000818:Animals; D001665:Binding Sites; D001923:Brain Chemistry; D002417:Cattle; D003000:Clonidine / Q000031:analogs & derivatives* / Q000378:metabolism*; D008168:Lung / Q000737:chemistry*; D000432:Methanol / Q000737:chemistry; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism*; D014020:Tissue Extracts / Q000737:chemistry*
D018341:Receptors, Adrenergic, alpha-2; D014020:Tissue Extracts; C055140:clonidine-displacing substance; D003000:Clonidine; D000432:Methanol