Specific binding of 3H-guanfacine to alpha 2-adrenoceptors in rat brain. Comparison with 3H-clonidine.
1. 3H-clonidine and the new antihypertensive drug, 3H-guanfacine (N-amino-2-[2,6-dichlorophenyl]-acetamide hydrochloride), bind with a high affinity to alpha 2-adrenoceptors in the rat central nervous system. 2. Dissociation curves for 3H-clonidine and 3H-guanfacine binding indicate the presence of high and low affinity binding sites. 3. In various rat brain regions, guanfacine is 0.5 to 8 times more selective for alpha-2 adrenoceptors than clonidine. 4. In the corpus striatum, dopamine is 7 times more potent at 3H-clonidine sites than at 3H-guanfacine sites. 5. In conclusion, the radioligand 3H-guanfacine appears more selective for alpha 2-adrenoceptors than 3H-clonidine.
D000818:Animals; D000959:Antihypertensive Agents / Q000378:metabolism*; D001337:Autonomic Agents / Q000494:pharmacology; D001665:Binding Sites / Q000187:drug effects; D001921:Brain / Q000378:metabolism*; D003000:Clonidine / Q000378:metabolism; D016316:Guanfacine; D006146:Guanidines / Q000378:metabolism*; D008297:Male; D010648:Phenylacetates / Q000378:metabolism*; D011224:Prazosin / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000378:metabolism*; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D014316:Tritium
D000959:Antihypertensive Agents; D001337:Autonomic Agents; D006146:Guanidines; D010648:Phenylacetates; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D014316:Tritium; D016316:Guanfacine; D003000:Clonidine; D011224:Prazosin