We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
In vivo studies on the effects of α<sub>1</sub>-adrenoceptor antagonists on pupil diameter and urethral tone in rabbits.
- Authors
Michel, Martin C.; Okutsu, Hiroko; Noguchi, Yukiko; Suzuki, Masanori; Ohtake, Akiyoshi; Yuyama, Hironori; Yanai-Inamura, Hiroko; Ukai, Masashi; Watanabe, Mai; Someya, Akiyoshi; Sasamata, Masao
- Abstract
α1-Adrenoceptors mediate contraction of iris dilator smooth muscle and hence pupil dilatation. We compared the ability of i.v. bolus injections of alfuzosin, doxazosin, naftopidil, prazosin, tamsulosin and terazosin to antagonise phenylephrine-induced mydriasis relative to their potency for inhibiting phenylephrine-induced elevations of intraurethral pressure (IUP) in rabbits. Moreover, we compared the ability of these drugs to induce miosis in conscious rabbits in the absence of phenylephrine. All antagonists inhibited the effects of phenylephrine on pupil size and IUP, and the ratio of the respective ED50 values was close to unity in all cases. The doses required to induce statistically significant miosis in the absence of phenylephrine were 30- to 100-fold higher than those inhibiting phenylephrine-induced mydriasis for all antagonists, except for naftopidil. Moreover, the miotic effects of all α1-adrenoceptor antagonists were fully reversible within 8 h. We conclude that alfuzosin, doxazosin, naftopidil, prazosin, tamsulosin and terazosin inhibit phenylephrine-induced mydriasis in the same dose range as they inhibit elevations in IUP. Higher doses of all antagonists are required to induce miosis in the absence of an exogenous agonist, and such miosis is always reversible within hours.
- Subjects
ADRENERGIC receptors; ADRENERGIC alpha blockers; DRUG receptors; SYMPATHETIC nervous system; DOXAZOSIN; ANTICHOLESTEREMIC agents; ANTIHYPERTENSIVE agents
- Publication
Naunyn-Schmiedeberg's Archives of Pharmacology, 2006, Vol 372, Issue 5, p346
- ISSN
0028-1298
- Publication type
Article
- DOI
10.1007/s00210-006-0034-9