Abstract
1. Phenylephrine-induced contractions of rabbit isolated trigone and urethra were antagonized in a competitive manner by alfuzosin (pA2 7.44 and 7.30, respectively) and prazosin. 2. The characteristics of [3H]-prazosin binding to human prostatic adenoma tissue were evaluated. [3H]-prazosin was potently displaced by alpha 1-adrenoceptor specific agents including alfuzosin, its (+)- and (-)-enantiomers and prazosin (IC50 0.035, 0.023, 0.019 and 0.004 microM, respectively), but only weakly by alpha 2-adrenoceptor selective agents, for example, yohimbine (IC50 = 6.0 microM). 3. In the pithed rat, alfuzosin (0.03-0.3 mg kg-1, i.v.) markedly inhibited pressor responses produced by the alpha 1-selective agonist, cirazoline but inhibited only slightly responses to the alpha 2-selective agonist, UK 14,304. Alfuzosin (1 mg kg-1, i.v.) had minimal effects against responses mediated by stimulation of prejunctional alpha 2-receptors (UK 14,304-induced inhibition of sympathetic tachycardia). 4. In the anaesthetized cat, alfuzosin (0.001-1 mg kg-1, i.v.) and prazosin (0.001-0.3 mg kg-1, i.v.) produced dose-related inhibition of the increases in urethral pressure caused by stimulation of sympathetic hypogastric nerves. Prazosin was approximately 5 fold more potent than alfuzosin. When phenylephrine was employed to induce urethral and vascular alpha 1-mediated tone simultaneously, prazosin inhibited both stimuli with similar potency whereas alfusozin was 3-5 fold more potent against elevated urethral pressure. This functional uroselectivity of alfuzosin was more evident by the intraduodenal route, since doses of 0.03 and 0.1 mg kg-1 alfuzosin inhibited urethral pressure with minimal effects on arterial blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)
Full text
PDFSelected References
These references are in PubMed. This may not be the complete list of references from this article.
- Beckeringh J. J., Thoolen M. J., De Jonge A., Wilffert B., Timmermans P. B., Van Zwieten P. A. The contractions induced in rat and guinea-pig aortic strips by the alpha 2-adrenoceptor selective agonists B-HT 920 and UK 14,304 are mediated by alpha 1-adrenoceptors. Eur J Pharmacol. 1984 Sep 17;104(3-4):197–203. doi: 10.1016/0014-2999(84)90394-7. [DOI] [PubMed] [Google Scholar]
- Caine M. The present role of alpha-adrenergic blockers in the treatment of benign prostatic hypertrophy. J Urol. 1986 Jul;136(1):1–4. doi: 10.1016/s0022-5347(17)44709-4. [DOI] [PubMed] [Google Scholar]
- Furuya S., Kumamoto Y., Yokoyama E., Tsukamoto T., Izumi T., Abiko Y. Alpha-adrenergic activity and urethral pressure in prostatic zone in benign prostatic hypertrophy. J Urol. 1982 Oct;128(4):836–839. doi: 10.1016/s0022-5347(17)53216-4. [DOI] [PubMed] [Google Scholar]
- Gup D. I., Shapiro E., Baumann M., Lepor H. Autonomic receptors in human prostate adenomas. J Urol. 1990 Jan;143(1):179–185. doi: 10.1016/s0022-5347(17)39906-8. [DOI] [PubMed] [Google Scholar]
- Hedlund H., Andersson K. E., Ek A. Effects of prazosin in patients with benign prostatic obstruction. J Urol. 1983 Aug;130(2):275–278. doi: 10.1016/s0022-5347(17)51106-4. [DOI] [PubMed] [Google Scholar]
- Hedlund H., Andersson K. E., Larsson B. Alpha-adrenoceptors and muscarinic receptors in the isolated human prostate. J Urol. 1985 Dec;134(6):1291–1298. doi: 10.1016/s0022-5347(17)47714-7. [DOI] [PubMed] [Google Scholar]
- Hieble J. P., Caine M. Etiology of benign prostatic hyperplasia and approaches to its pharmacological management. Fed Proc. 1986 Oct;45(11):2601–2603. [PubMed] [Google Scholar]
- Hieble J. P., Caine M., Zalaznik E. In vitro characterization of the alpha-adrenoceptors in human prostate. Eur J Pharmacol. 1985 Jan 2;107(2):111–117. doi: 10.1016/0014-2999(85)90048-2. [DOI] [PubMed] [Google Scholar]
- James S., Chapple C. R., Phillips M. I., Greengrass P. M., Davey M. J., Turner-Warwick R. T., Milroy E. J., Burnstock G. Autoradiographic analysis of alpha-adrenoceptors and muscarinic cholinergic receptors in the hyperplastic human prostate. J Urol. 1989 Aug;142(2 Pt 1):438–444. doi: 10.1016/s0022-5347(17)38780-3. [DOI] [PubMed] [Google Scholar]
- Jardin A., Bensadoun H., Delauche-Cavallier M. C., Attali P. Alfuzosin for treatment of benign prostatic hypertrophy. The BPH-ALF Group. Lancet. 1991 Jun 15;337(8755):1457–1461. doi: 10.1016/0140-6736(91)93140-5. [DOI] [PubMed] [Google Scholar]
- Kitada S., Kumazawa J. Pharmacological characteristics of smooth muscle in benign prostatic hyperplasia and normal prostatic tissue. J Urol. 1987 Jul;138(1):158–160. doi: 10.1016/s0022-5347(17)43034-5. [DOI] [PubMed] [Google Scholar]
- Kunisawa Y., Kawabe K., Niijima T., Honda K., Takenaka T. A pharmacological study of alpha adrenergic receptor subtypes in smooth muscle of human urinary bladder base and prostatic urethra. J Urol. 1985 Aug;134(2):396–398. doi: 10.1016/s0022-5347(17)47185-0. [DOI] [PubMed] [Google Scholar]
- Langer S. Z., Massingham R., Shepperson N. B. Presence of postsynaptic alpha 2-adrenoreceptors of predominantly extrasynaptic location in the vascular smooth muscle of the dog hind limb. Clin Sci (Lond) 1980 Dec;59 (Suppl 6):225s–228s. doi: 10.1042/cs059225s. [DOI] [PubMed] [Google Scholar]
- Langer S. Z. Presynaptic regulation of catecholamine release. Biochem Pharmacol. 1974 Jul 1;23(13):1793–1800. doi: 10.1016/0006-2952(74)90187-7. [DOI] [PubMed] [Google Scholar]
- Lepor H., Knapp-Maloney G., Sunshine H. A dose titration study evaluating terazosin, a selective, once-a-day alpha 1-blocker for the treatment of symptomatic benign prostatic hyperplasia. J Urol. 1990 Dec;144(6):1393–1398. doi: 10.1016/s0022-5347(17)39751-3. [DOI] [PubMed] [Google Scholar]
- Lomasney J. W., Cotecchia S., Lorenz W., Leung W. Y., Schwinn D. A., Yang-Feng T. L., Brownstein M., Lefkowitz R. J., Caron M. G. Molecular cloning and expression of the cDNA for the alpha 1A-adrenergic receptor. The gene for which is located on human chromosome 5. J Biol Chem. 1991 Apr 5;266(10):6365–6369. [PubMed] [Google Scholar]
- Mitchell M. R., Powell T., Terrar D. A., Twist V. W. Ryanodine prolongs Ca-currents while suppressing contraction in rat ventricular muscle cells. Br J Pharmacol. 1984 Jan;81(1):13–15. doi: 10.1111/j.1476-5381.1984.tb10735.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ueda S., Satake N., Shibata S. Alpha 1- and alpha 2-adrenoceptors in the smooth muscle of isolated rabbit urinary bladder and urethra. Eur J Pharmacol. 1984 Aug 17;103(3-4):249–254. doi: 10.1016/0014-2999(84)90484-9. [DOI] [PubMed] [Google Scholar]
- Yamada S., Ashizawa N., Ushijima H., Nakayama K., Hayashi E., Honda K. Alpha-1 adrenoceptors in human prostate: characterization and alteration in benign prostatic hypertrophy. J Pharmacol Exp Ther. 1987 Jul;242(1):326–330. [PubMed] [Google Scholar]