{
    "abstract": "Previously, we reported that the alpha(1A)-adrenoceptor, but not the alpha(1D)-adrenoceptor, mediates pupillary dilation elicited by sympathetic nerve stimulation in rats. This study was undertaken to further characterize the alpha-adrenoceptor subtypes mediating pupillary dilation in response to both neural and agonist activation. Pupillary dilator response curves were generated by intravenous injection of norepinephrine in pentobarbital-anesthetized rats. Involvement of alpha(1)-adrenoceptors was established as mydriatic responses were inhibited by systemic administration of nonselective alpha-adrenoceptor antagonists, phentolamine (0.3-3 mg/kg) and phenoxybenzamine (0.03-0.3 mg/kg), as well as by the selective alpha(1)-adrenoceptor antagonist, prazosin (0.3 mg/kg). The alpha(2)-adrenoceptor antagonist, rauwolscine (0.5 mg/kg), was without antagonistic effects. alpha(1A)-Adrenoceptor selective antagonists, 2-([2,6-dimethoxyphenoxyethyl]aminomethyl)-1,4-benzodioxane (WB-4101; 0.1-1 mg/kg) and 5-methylurapidil (0.1-1 mg/kg), the alpha(1B)-adrenoceptor selective antagonist, 4-amino-2-[4-[1-(benzyloxycarbonyl)-2(S)- [[(1,1-dimethylethyl)amino]carbonyl]-piperazinyl]-6,7-dimethoxyquinazoline (L-765314; 0.3-1 mg/kg), as well as the alpha(1D)-adrenoceptor selective antagonist, 8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4.5]decane-7,9-dione (BMY-7378; 1 mg/kg), were used to delineate the adrenoceptor subtypes involved. Mydriatic responses to norepinephrine were significantly antagonized by intravenous administration of both WB-4101 and 5-methylurapidil, but neither by L-765314 nor by BMY-7378. L-765314 (0.3-3 mg/kg, i.v.) was also ineffective in inhibiting the mydriasis evoked by cervical sympathetic nerve stimulation. These results suggest that alpha(1B)-adrenoceptors do not mediate sympathetic mydriasis in rats, and that the alpha(1A)-adrenoceptor is the exclusive subtype mediating mydriatic responses in this species.",
    "authors": [
        {
            "affiliation": "Department of Cell Biology, University of Oklahoma College of Medicine, Oklahoma City, OK 73190, USA. yongxin-yu@ouhsc.edu",
            "firstname": "Yongxin",
            "initials": "Y",
            "lastname": "Yu"
        },
        {
            "affiliation": null,
            "firstname": "Michael C",
            "initials": "MC",
            "lastname": "Koss"
        }
    ],
    "conclusions": null,
    "copyrights": null,
    "doi": "10.1016/s0014-2999(03)01824-7",
    "journal": "European journal of pharmacology",
    "keywords": [],
    "methods": null,
    "publication_date": "2003-06-24",
    "pubmed_id": "12818701",
    "results": null,
    "title": "Functional characterization of alpha-adrenoceptors mediating pupillary dilation in rats.",
    "xml": "<Element 'PubmedArticle' at 0x788502625b70>"
}