Abstract
1. Peristaltic contractions were induced in segments of rat ileum by raising the intramural pressure. A mean pressure of 4.3 +/- 0.2 cmH2O (n = 112) was required to initiate rhythmic contractions of the longitudinal muscle (preparatory phase) and associated volume expulsions caused by circular muscle contraction. The frequency of peristalsis remained constant over two 15 min periods of stimulation. 2. The alpha 2-adreoceptor agonists, clonidine, UK 14,304, B-HT 920, B-HT 933 and the selective alpha 2A-agonists, oxymetazoline and guanfacine, caused concentration-dependent inhibition of peristaltic contractions. The potency order and IC50 values (nM) were: clonidine (2.81) > or = oxymetazoline (4.23) > or = UK 14,304 (4.48) > or = guanfacine (5.51) > B-HT 920 (78.72) > B-HT 933 (442.48). 3. High concentrations of clonidine, amounting to more than 10 and 100 times the IC50 value in the peristaltic reflex (30 and 300 nM respectively), failed to inhibit the cholinergic contractile response to transmural electrical stimulation over the range of 2.5 to 40 Hz. 4. alpha 2-Adrenoceptor antagonists were used to determine the subtype of presynaptic alpha 2-adrenoceptor in rat ileum. All the antagonists tested caused parallel shifts to the right of the concentration-response regression line to clonidine and none, except ARC 239, influenced the rate of peristalsis. However, ARC 239 significantly decreased the frequency of control period peristaltic contractions. The order of affinity of the antagonists against clonidine (pKB values in parentheses) was RX 821002 (8.99) > phentolamine (8.07) > BRL 44408 (7.43) > or = rauwolscine (7.41) > or = yohimbine (7.28) > prazosin (5.86) > or = ARC 239 (5.74). 5. These results, when compared with binding and functional data from various other tissues and cell lines, are consistent with the presence of presynaptic alpha 2D-adrenoceptors in rat ileum. Further evidence is provided that this subtype of alpha 2-adrenoceptor is probably located proximal to the final cholinergic neurones in the reflex arc.
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- ARUNLAKSHANA O., SCHILD H. O. Some quantitative uses of drug antagonists. Br J Pharmacol Chemother. 1959 Mar;14(1):48–58. doi: 10.1111/j.1476-5381.1959.tb00928.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Andréjak M., Pommier Y., Mouillé P., Schmitt H. Effects of some alpha-adrenoceptor agonists and antagonists on the guinea-pig ileum. Naunyn Schmiedebergs Arch Pharmacol. 1980 Oct;314(1):83–87. doi: 10.1007/BF00498434. [DOI] [PubMed] [Google Scholar]
- Blaxall H. S., Murphy T. J., Baker J. C., Ray C., Bylund D. B. Characterization of the alpha-2C adrenergic receptor subtype in the opossum kidney and in the OK cell line. J Pharmacol Exp Ther. 1991 Oct;259(1):323–329. [PubMed] [Google Scholar]
- Bylund D. B., Ray-Prenger C., Murphy T. J. Alpha-2A and alpha-2B adrenergic receptor subtypes: antagonist binding in tissues and cell lines containing only one subtype. J Pharmacol Exp Ther. 1988 May;245(2):600–607. [PubMed] [Google Scholar]
- Bylund D. B. Subtypes of alpha 2-adrenoceptors: pharmacological and molecular biological evidence converge. Trends Pharmacol Sci. 1988 Oct;9(10):356–361. doi: 10.1016/0165-6147(88)90254-4. [DOI] [PubMed] [Google Scholar]
- Cambridge D. UK-14,304, a potent and selective alpha2-agonist for the characterisation of alpha-adrenoceptor subtypes. Eur J Pharmacol. 1981 Jul 10;72(4):413–415. doi: 10.1016/0014-2999(81)90588-4. [DOI] [PubMed] [Google Scholar]
- Coupar I. M., De Luca A. Opiate and opiate antidiarrhoeal drug action on rat isolated intestine. J Auton Pharmacol. 1994 Feb;14(1):69–78. doi: 10.1111/j.1474-8673.1994.tb00591.x. [DOI] [PubMed] [Google Scholar]
- Devedjian J. C., Esclapez F., Denis-Pouxviel C., Paris H. Further characterization of human alpha 2-adrenoceptor subtypes: [3H]RX821002 binding and definition of additional selective drugs. Eur J Pharmacol. 1994 Jan 24;252(1):43–49. doi: 10.1016/0014-2999(94)90573-8. [DOI] [PubMed] [Google Scholar]
- Doherty N. S., Hancock A. A. Role of alpha-2 adrenergic receptors in the control of diarrhea and intestinal motility. J Pharmacol Exp Ther. 1983 May;225(2):269–274. [PubMed] [Google Scholar]
- Harrison J. K., D'Angelo D. D., Zeng D. W., Lynch K. R. Pharmacological characterization of rat alpha 2-adrenergic receptors. Mol Pharmacol. 1991 Sep;40(3):407–412. [PubMed] [Google Scholar]
- Kobinger W. Rudolf Buchheim lecture. Drugs as tools in research on adrenoceptors. Naunyn Schmiedebergs Arch Pharmacol. 1986 Feb;332(2):113–123. doi: 10.1007/BF00511400. [DOI] [PubMed] [Google Scholar]
- Kurose H., Arriza J. L., Lefkowitz R. J. Characterization of alpha 2-adrenergic receptor subtype-specific antibodies. Mol Pharmacol. 1993 Mar;43(3):444–450. [PubMed] [Google Scholar]
- Lanier S. M., Downing S., Duzic E., Homcy C. J. Isolation of rat genomic clones encoding subtypes of the alpha 2-adrenergic receptor. Identification of a unique receptor subtype. J Biol Chem. 1991 Jun 5;266(16):10470–10478. [PubMed] [Google Scholar]
- Lattimer N., Rhodes K. F. A difference in the affinity of some selective alpha 2-adrenoceptor antagonists when compared on isolated vasa deferentia of rat and rabbit. Naunyn Schmiedebergs Arch Pharmacol. 1985 May;329(3):278–281. doi: 10.1007/BF00501880. [DOI] [PubMed] [Google Scholar]
- Limberger N., Trendelenburg A. U., Starke K. Pharmacological characterization of presynaptic alpha 2-autoreceptors in rat submaxillary gland and heart atrium. Br J Pharmacol. 1992 Sep;107(1):246–255. doi: 10.1111/j.1476-5381.1992.tb14494.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lorenz W., Lomasney J. W., Collins S., Regan J. W., Caron M. G., Lefkowitz R. J. Expression of three alpha 2-adrenergic receptor subtypes in rat tissues: implications for alpha 2 receptor classification. Mol Pharmacol. 1990 Nov;38(5):599–603. [PubMed] [Google Scholar]
- MacKinnon A. C., Spedding M., Brown C. M. Alpha 2-adrenoceptors: more subtypes but fewer functional differences. Trends Pharmacol Sci. 1994 Apr;15(4):119–123. doi: 10.1016/0165-6147(94)90048-5. [DOI] [PubMed] [Google Scholar]
- Michel A. D., Loury D. N., Whiting R. L. Differences between the alpha 2-adrenoceptor in rat submaxillary gland and the alpha 2A-and alpha 2B-adrenoceptor subtypes. Br J Pharmacol. 1989 Nov;98(3):890–897. doi: 10.1111/j.1476-5381.1989.tb14618.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Murphy T. J., Bylund D. B. Characterization of alpha-2 adrenergic receptors in the OK cell, an opossum kidney cell line. J Pharmacol Exp Ther. 1988 Feb;244(2):571–578. [PubMed] [Google Scholar]
- Paris H., Voisin T., Remaury A., Rouyer-Fessard C., Daviaud D., Langin D., Laburthe M. Alpha-2 adrenoceptor in rat jejunum epithelial cells: characterization with [3H]RX821002 and distribution along the villus-crypt axis. J Pharmacol Exp Ther. 1990 Sep;254(3):888–893. [PubMed] [Google Scholar]
- Remaury A., Paris H. The insulin-secreting cell line, RINm5F, expresses an alpha-2D adrenoceptor and nonadrenergic idazoxan-binding sites. J Pharmacol Exp Ther. 1992 Jan;260(1):417–426. [PubMed] [Google Scholar]
- Renouard A., Widdowson P. S., Millan M. J. Multiple alpha 2 adrenergic receptor subtypes. I. Comparison of [3H]RX821002-labeled rat R alpha-2A adrenergic receptors in cerebral cortex to human H alpha2A adrenergic receptor and other populations of alpha-2 adrenergic subtypes. J Pharmacol Exp Ther. 1994 Sep;270(3):946–957. [PubMed] [Google Scholar]
- Sallés J., Giraldo J., Badia A. Analysis of agonism at functional prejunctional alpha 2-adrenoceptors of rat vas deferens using operational and null approaches. Eur J Pharmacol. 1994 Jun 13;258(3):229–238. doi: 10.1016/0014-2999(94)90484-7. [DOI] [PubMed] [Google Scholar]
- Seutin V., Scuvée-Moreau J., Giesbers I., Massotte L., Dresse A. Effect of BHT 920 on monoaminergic neurons of the rat brain: an electrophysiological in vivo and in vitro study. Naunyn Schmiedebergs Arch Pharmacol. 1990 Nov;342(5):502–507. doi: 10.1007/BF00169036. [DOI] [PubMed] [Google Scholar]
- Shen K. Z., Barajas-Lopez C., Surprenant A. Functional characterization of neuronal pre and postsynaptic alpha 2-adrenoceptor subtypes in guinea-pig submucosal plexus. Br J Pharmacol. 1990 Dec;101(4):925–931. doi: 10.1111/j.1476-5381.1990.tb14182.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Simonneaux V., Ebadi M., Bylund D. B. Identification and characterization of alpha 2D-adrenergic receptors in bovine pineal gland. Mol Pharmacol. 1991 Aug;40(2):235–241. [PubMed] [Google Scholar]
- Smith K., Docherty J. R. Are the prejunctional alpha 2-adrenoceptors of the rat vas deferens and submandibular gland of the alpha 2A- or alpha 2D-subtype? Eur J Pharmacol. 1992 Aug 25;219(2):203–210. doi: 10.1016/0014-2999(92)90297-h. [DOI] [PubMed] [Google Scholar]
- Trendelenburg A. U., Limberger N., Starke K. Presynaptic alpha 2-autoreceptors in brain cortex: alpha 2D in the rat and alpha 2A in the rabbit. Naunyn Schmiedebergs Arch Pharmacol. 1993 Jul;348(1):35–45. doi: 10.1007/BF00168534. [DOI] [PubMed] [Google Scholar]
- Uhlén S., Wikberg J. E. Delineation of rat kidney alpha 2A- and alpha 2B-adrenoceptors with [3H]RX821002 radioligand binding: computer modelling reveals that guanfacine is an alpha 2A-selective compound. Eur J Pharmacol. 1991 Sep 17;202(2):235–243. doi: 10.1016/0014-2999(91)90299-6. [DOI] [PubMed] [Google Scholar]
- Wikberg J. Localization of adrenergic receptors in guinea pig ileum and rabbit jejunum to cholinergic neurons and to smooth muscle cells. Acta Physiol Scand. 1977 Feb;99(2):190–207. doi: 10.1111/j.1748-1716.1977.tb10370.x. [DOI] [PubMed] [Google Scholar]