<p>α<sub>1</sub>- and α<sub>2</sub>-Adrenoceptors are involved in various physiological events in the eye: blood flow regulation, aqueous humor dynamics and pupil regulation. The α<sub>1</sub>- and α<sub>2</sub>-adrenoceptors can be further subdivided into six subtypes (α<sub>1A</sub>, α<sub>1B</sub>, α<sub>1D</sub>, α<sub>2A</sub> , α<sub>2B</sub>, and α<sub>2C</sub> ). Currently available α1- and α<sub>2</sub>-adrenergic drugs are not selective for the different subtypes and some ocular adrenergics have undesirable side-effects, both local and systemic. A better understanding of the subtype distribution in the eye would be useful when designing new drugs with greater efficacy and fewer adverse effects; this applies especially to the treatment of glaucoma. The purpose of the thesis was therefore to identify and localize the different subtypes of α<sub>1</sub>- and α<sub>2</sub>-adrenoceptors in the eye. </p><p>The identities of the α<sub>1</sub>-adrenoceptor subtypes were studied in various parts of pig and albino rabbit eyes by radioligand binding. In the pig retina and in the albino rabbit iris, ciliary body and retina, mixed populations of α<sub>1A</sub>- and α<sub>1B</sub>-adrenoceptors were localized. In the rabbit choroid only the α<sub>1A</sub>-adrenoceptor subtype was detected. </p><p>The α<sub>2</sub>-adrenoceptor subtypes were also characterized by radioligand binding, in different parts of the pig eye. In the iris, ciliary body and choroid, only α<sub>2A</sub>-adrenoceptors were localized, while in the retina, mostly α<sub>2A</sub>-adrenoceptors and a minor population of α<sub>2C</sub>-adrenoceptors were identified. High densities of α<sub>2A</sub>-adrenoceptors were found in the ciliary body and choroid.</p><p>The effect of α<sub>2</sub>-adrenoceptor agonists on the porcine ciliary artery was studied on a small-vessel myograph. α<sub>2</sub>-Adrenoceptor agonists proved to be potent vasoconstrictors in the porcine ciliary artery and it was found that the vasoconstriction induced by brimonidine was mediated by the α<sub>A</sub>-adrenoceptor.</p>
| Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:uu-1383 |
| Date | January 2001 |
| Creators | Wikberg-Matsson, Anna |
| Publisher | Uppsala University, Department of Neuroscience, Uppsala : Acta Universitatis Upsaliensis |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, comprehensive summary, text |
| Relation | Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, 0282-7476 ; 1058 |
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