{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,10]],"date-time":"2026-06-10T17:03:06Z","timestamp":1781110986441,"version":"3.54.1"},"reference-count":0,"publisher":"National Academy of Sciences","issue":"8","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[1976,8]]},"abstract":"<jats:p>The potent alpha-adrenoreceptor blocking agent, azapetine, has been catalytically reduced with tritium gas to form [3H]dihydroazapetine. [3H]Dihydroazapetine retains significant ability to block alpha-adrenoreceptors and has been used as a ligand to study the receptor in a subcellular fraction containing membrane fragments from rat vas deferens. Specific binding of [3H]dihydroazapetine rapidly reaches equilibrium and is also reversible and saturable with a dissociation constant similar to that determined pharmacologically. The binding capacity is approximately 40 pmol\/mg of protein. All alpha-adrenergic blockers tested were able to inhibit specific binding. High concentrations of alprenolol, atropine, or chlorpheniramine had no effect. In addition, all alpha-adrenergic agonists of the imidazoline class inhibit binding in low concentrations, whereas soterenol or carbamylcholine did not. There is good correlation (r=0.84) between blockade or stimulation of the receptor in intact tissues and inhibition of binding of [3H]dihydroazapetine to the subcellular fraction. These findings suggest that the fraction contains alpha-adrenoreceptor-related proteins. Alpha-adrenergic agonists structurally related to norepinephrine caused a stereoselective increase in binding in favor of the (-)-isomer, possibly reflecting an allosteric interaction at a different binding site on the receptor protein. The possibility of two different modes of binding for structurally dissimilar agonists is suggested.<\/jats:p>","DOI":"10.1073\/pnas.73.8.2730","type":"journal-article","created":{"date-parts":[[2006,5,31]],"date-time":"2006-05-31T03:20:54Z","timestamp":1149045654000},"page":"2730-2734","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":22,"title":["Binding of [3H]dihydroazapetine to alpha-adrenoreceptor-related proteins from rat vas deferens."],"prefix":"10.1073","volume":"73","author":[{"suffix":"Jr","given":"R R","family":"Ruffolo","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J W","family":"Fowble","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"D D","family":"Miller","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"P N","family":"Patil","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[1976,8]]},"container-title":["Proceedings of the National Academy of Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pnas.org\/doi\/pdf\/10.1073\/pnas.73.8.2730","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,4,13]],"date-time":"2022-04-13T11:01:12Z","timestamp":1649847672000},"score":1,"resource":{"primary":{"URL":"https:\/\/pnas.org\/doi\/full\/10.1073\/pnas.73.8.2730"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1976,8]]},"references-count":0,"journal-issue":{"issue":"8","published-print":{"date-parts":[[1976,8]]}},"alternative-id":["10.1073\/pnas.73.8.2730"],"URL":"https:\/\/doi.org\/10.1073\/pnas.73.8.2730","relation":{},"ISSN":["0027-8424","1091-6490"],"issn-type":[{"value":"0027-8424","type":"print"},{"value":"1091-6490","type":"electronic"}],"subject":[],"published":{"date-parts":[[1976,8]]},"assertion":[{"value":"1976-08-01","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}