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. 1995 Jan;114(2):339–348. doi: 10.1111/j.1476-5381.1995.tb13232.x

The use of receptor desensitization to analyse CCKA and CCKB/gastrin receptors coupled to contraction in guinea-pig stomach muscle.

L A Bishop 1, V P Gerskowitch 1, R A Hull 1, N P Shankley 1, J W Black 1
PMCID: PMC1510258  PMID: 7881733

Abstract

1. The results of previous studies have been in conflict with respect to the involvement of specific cholecystokinin (CCKA) and CCKB/gastrin receptors in guinea-pig gastric muscle. Here, in an in vitro, guinea-pig gastric muscle assay, pentagastrin (PG) and tetragastrin (TG) behaved as high potency agonists and produced symmetrical concentration-effect curves. In contrast, cholecystokinin-octapeptide (CCK-8), while also behaving as a high potency agonist, produced flat asymmetrical curves. Unlike recent data reported using this tissue (Boyle et al., 1993), the CCKA receptor-selective antagonist, devazepide (3, 10, 30 nM) produced a rightward shift of the upper region of the CCK-8 curve rendering it biphasic. The lower phase was abolished by the CCKB/gastrin receptor-selective antagonist, L-365260 (300 nM) indicating that the contractile effects of CCK-8 in this tissue are mediated by both receptor types. 2. L-365260 produced a concentration-dependent, parallel rightward displacement of PG concentration-effect curves. However, a flat Schild plot slope parameter (0.77 +/- 0.06) was obtained. Therefore, an empirical pA2 value of 8.64 +/- 0.21 was estimated from the smallest dose ratio. This value is consistent with published values characteristic of an interaction at CCKB/gastrin receptors. 3. TG (1 microM) was used to densensitize selectively the CCKB/gastrin receptors in the gastric muscle assay and thereby expose a population of receptors capable of responding to subsequent stimulation by CCK-8 but not by PG. The selectivity of TG for CCKB/gastrin- over CCKA receptors was demonstrated by its low efficacy compared to CCK-8 in the guinea-pig gallbladder assay, a tissue shown previously to contain a homogeneous population of CCKA receptors. In TG-desensitized gastric muscle, CCK-8 concentration-effect curves were symmetrical and could be displaced in a simple parallel fashion by devazepide at nanomolar concentrations consistent with an interaction at CCKA receptors (pKB approximately 10). 4. These results indicate that the guinea-pig gastric muscle contains both CCKA- and CCKB/gastrin receptors and the effects of CCK-8 are mediated via both of these receptors. Notwithstanding the complexity of the behaviour of L-365260, it was possible to obtain a reasonable description of the system using a simple 2-receptor model in which the effects of individual receptor activation were assumed to be additive. The absence of a simple competitive interaction of PG with L-365260 may indicate, for example, non-homogeneity of CCKB/gastrin receptors or lack of concentration equilibrium between the bath and the receptor biophase.

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Selected References

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  1. Bishop L. A., Gerskowitch V. P., Hull R. A., Shankley N. P., Black J. W. Combined dose-ratio analysis of cholecystokinin receptor antagonists, devazepide, lorglumide and loxiglumide in the guinea-pig gall bladder. Br J Pharmacol. 1992 May;106(1):61–66. doi: 10.1111/j.1476-5381.1992.tb14293.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Bitar K. N., Makhlouf G. M. Receptors on smooth muscle cells: characterization by contraction and specific antagonists. Am J Physiol. 1982 Apr;242(4):G400–G407. doi: 10.1152/ajpgi.1982.242.4.G400. [DOI] [PubMed] [Google Scholar]
  3. Black J. W., Shankley N. P. The isolated stomach preparation of the mouse: a physiological unit for pharmacological analysis. Br J Pharmacol. 1985 Nov;86(3):571–579. doi: 10.1111/j.1476-5381.1985.tb08933.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Bock M. G., DiPardo R. M., Evans B. E., Rittle K. E., Freidinger R. M., Chang R. S., Lotti V. J. Cholecystokinin antagonists. Synthesis and biological evaluation of 3-substituted 1,4-benzodiazepin-2-amines. J Med Chem. 1988 Jan;31(1):264–268. doi: 10.1021/jm00396a042. [DOI] [PubMed] [Google Scholar]
  5. Boyle S. J., Tang K. W., Woodruff G. N., McKnight A. T. Characterization of CCK receptors in a novel smooth muscle preparation from the guinea-pig stomach by use of the selective antagonists CI-988, L-365,260 and devazepide. Br J Pharmacol. 1993 Aug;109(4):913–917. doi: 10.1111/j.1476-5381.1993.tb13707.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Brand S. J., Andersen B. N., Rehfeld J. F. Complete tyrosine-O-sulphation of gastrin in neonatal rat pancreas. 1984 May 31-Jun 6Nature. 309(5967):456–458. doi: 10.1038/309456a0. [DOI] [PubMed] [Google Scholar]
  7. Chang R. S., Lotti V. J. Biochemical and pharmacological characterization of an extremely potent and selective nonpeptide cholecystokinin antagonist. Proc Natl Acad Sci U S A. 1986 Jul;83(13):4923–4926. doi: 10.1073/pnas.83.13.4923. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Chang R. S., Lotti V. J., Chen T. B. Characterization of [3H](+/-)L-364,718 binding to solubilized cholecystokinin (CCK) receptors of rat pancreas. Biochem Pharmacol. 1987 May 15;36(10):1709–1714. doi: 10.1016/0006-2952(87)90057-8. [DOI] [PubMed] [Google Scholar]
  9. Dal Forno G., Pietra C., Urciuoli M., van Amsterdam F. T., Toson G., Gaviraghi G., Trist D. Evidence for two cholecystokinin receptors mediating the contraction of the guinea pig isolated ileum longitudinal muscle myenteric plexus. J Pharmacol Exp Ther. 1992 Jun;261(3):1056–1063. [PubMed] [Google Scholar]
  10. Eckman D. M., Frankovich J. D., Keef K. D. Comparison of the actions of acetylcholine and BRL 38227 in the guinea-pig coronary artery. Br J Pharmacol. 1992 May;106(1):9–16. doi: 10.1111/j.1476-5381.1992.tb14285.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Evans B. E., Bock M. G., Rittle K. E., DiPardo R. M., Whitter W. L., Veber D. F., Anderson P. S., Freidinger R. M. Design of potent, orally effective, nonpeptidal antagonists of the peptide hormone cholecystokinin. Proc Natl Acad Sci U S A. 1986 Jul;83(13):4918–4922. doi: 10.1073/pnas.83.13.4918. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Grider J. R., Makhlouf G. M. Distinct receptors for cholecystokinin and gastrin on muscle cells of stomach and gallbladder. Am J Physiol. 1990 Aug;259(2 Pt 1):G184–G190. doi: 10.1152/ajpgi.1990.259.2.G184. [DOI] [PubMed] [Google Scholar]
  13. Holland J., Hirst B. H., Shaw B. Structure-activity studies with cholecystokinin on gastric secretion in the cat. Peptides. 1982 Nov-Dec;3(6):891–895. doi: 10.1016/0196-9781(82)90056-0. [DOI] [PubMed] [Google Scholar]
  14. Huang S. C., Zhang L., Chiang H. C., Wank S. A., Maton P. N., Gardner J. D., Jensen R. T. Benzodiazepine analogues L365,260 and L364,718 as gastrin and pancreatic CCK receptor antagonists. Am J Physiol. 1989 Jul;257(1 Pt 1):G169–G174. doi: 10.1152/ajpgi.1989.257.1.G169. [DOI] [PubMed] [Google Scholar]
  15. Jenkinson D. H. How we describe competitive antagonists: three questions of usage. Trends Pharmacol Sci. 1991 Feb;12(2):53–54. doi: 10.1016/0165-6147(91)90497-g. [DOI] [PubMed] [Google Scholar]
  16. Lemoine H., Kaumann A. J. A model for the interaction of competitive antagonists with two receptor-subtypes characterized by a Schild-plot with apparent slope unity. Agonist-dependent enantiomeric affinity ratios for bupranolol in tracheae but not in right atria of guinea pigs. Naunyn Schmiedebergs Arch Pharmacol. 1983 Mar;322(2):111–120. doi: 10.1007/BF00512383. [DOI] [PubMed] [Google Scholar]
  17. Lotti V. J., Chang R. S. A new potent and selective non-peptide gastrin antagonist and brain cholecystokinin receptor (CCK-B) ligand: L-365,260. Eur J Pharmacol. 1989 Mar 21;162(2):273–280. doi: 10.1016/0014-2999(89)90290-2. [DOI] [PubMed] [Google Scholar]
  18. Louie D. S., Liang J. P., Owyang C. Characterization of a new CCK antagonist, L364,718: in vitro and in vivo studies. Am J Physiol. 1988 Sep;255(3 Pt 1):G261–G266. doi: 10.1152/ajpgi.1988.255.3.G261. [DOI] [PubMed] [Google Scholar]
  19. Lucaites V. L., Mendelsohn L. G., Mason N. R., Cohen M. L. CCK-8, CCK-4 and gastrin-induced contractions in guinea pig ileum: evidence for differential release of acetylcholine and substance P by CCK-A and CCK-B receptors. J Pharmacol Exp Ther. 1991 Feb;256(2):695–703. [PubMed] [Google Scholar]
  20. Menozzi D., Gardner J. D., Jensen R. T., Maton P. N. Properties of receptors for gastrin and CCK on gastric smooth muscle cells. Am J Physiol. 1989 Jul;257(1 Pt 1):G73–G79. doi: 10.1152/ajpgi.1989.257.1.G73. [DOI] [PubMed] [Google Scholar]
  21. Milnor W. R. Limitations of Schild plots in a two-receptor system: alpha adrenoceptors of vascular smooth muscle. J Pharmacol Exp Ther. 1986 Jul;238(1):237–241. [PubMed] [Google Scholar]
  22. Morley J. S., Tracy H. J., Gregory R. A. Structure-function relationships in the active C-terminal tetrapeptide sequence of gastrin. Nature. 1965 Sep 25;207(5004):1356–1359. doi: 10.1038/2071356a0. [DOI] [PubMed] [Google Scholar]
  23. Shankley N. P., Black J. W., Ganellin C. R., Mitchell R. C. Correlation between log POCT/H2O and pKB estimates for a series of muscarinic and histamine H2-receptor antagonists. Br J Pharmacol. 1988 May;94(1):264–274. doi: 10.1111/j.1476-5381.1988.tb11523.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Shankley N. P., Welsh N. J., Black J. W. Histamine dependence of pentagastrin-stimulated gastric acid secretion in rats. Yale J Biol Med. 1992 Nov-Dec;65(6):613–619. [PMC free article] [PubMed] [Google Scholar]
  25. Trist D. G., Leff P. Quantification of H2-agonism by clonidine and dimaprit in an adenylate cyclase assay. Agents Actions. 1985 Apr;16(3-4):222–226. doi: 10.1007/BF01983145. [DOI] [PubMed] [Google Scholar]

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