gastrin-17 and lorglumide

Cholecystokinin (CCK) and gastrin exert their influences via CCK receptors. This research was conducted to look at the responses of the sling and clasp fibers forming the human lower esophageal sphincter (LES) to CCK and gastrin, and the role of CCK receptors in the responses.. Muscle strips of sling and clasp fibers from the LES were obtained from patients undergoing subtotal esophagectomy. Isometric tension responses of the strips to CCK-8 and gastrin-17 were studied, and the maximum effect (E(max)) for each agonist was derived. CCK-A receptor antagonist, CR1409 and CCK-B antagonist, CR2945 were applied to sling and clasp fibers and their pK(B) values were calculated.. Sling fibers produced significant contractions following exposure to CCK-8 and gastrin-17, while clasp fibers had less responses to the two agents. CR1409 and CR2945 inhibited responses of sling to CCK-8 in a concentration-dependent fashion. The inhibition effects of the two antagonists on clasp fibers were not measurable because there was a mild contraction of the fiber in response to CCK-8.. The contractions generated by sling fibers following exposure to CCK and gastrin are greater than that produced by clasp fibers. CCK-A receptors are more important for the generation of contractions by the sling fibers, whereas both CCK-A and CCK-B receptors are involved in the functional regulation of the clasp fibers. [Corrections added after online publication 28 April 2008: in the Background and Aims section of the preceding abstract, all instances of 'CKK' were corrected to 'CCK'. In the final sentence of the abstract 'CCKA'was corrected to 'CCK-A'. In the article title '(CKK)' was corrected to '(CCK)'.].

Topics: Adult; Benzodiazepines; Dose-Response Relationship, Drug; Esophageal Sphincter, Lower; Esophagectomy; Female; Gastrins; Humans; In Vitro Techniques; Male; Middle Aged; Muscle Contraction; Myocytes, Smooth Muscle; Proglumide; Receptor, Cholecystokinin A; Receptor, Cholecystokinin B; Sincalide

1. The cardiovascular actions of cholecystokinin and related peptides were investigated in the pithed rat. The receptors and the mechanisms involved in these experiments were characterized. 2. Sulphated cholecystokinin octapeptide (sCCK-8, 0.1-100 nmol kg-1, i.v.) elicited a dose-dependent bradycardia and increase in mean arterial blood pressure. Neither gastrin-17 nor pentagastrin had any effect at concentrations up to 100 nmol kg-1. 3. Both the pressor response and bradycardia elicited by sCCK-8 were reduced by the selective CCKA receptor antagonists, devazepide (0.5-50 nmol kg-1) and lorglumide (1-7 mumol kg-1). The selective CCKB receptor antagonists, CI-988 (1 mumol kg-1) and L-365,260 (15 mumol kg-1) did not inhibit the effects of sCCK-8. 4. The pressor response induced with sCCK-8 was reduced by treatment with either phentolamine (3 mumol kg-1) or guanethidine (2 mumol kg-1) and was unaffected by treatment with propranolol, atropine or hexamethonium. The pressor response also persisted following bilateral adrenalectomy. 5. The bradycardia induced with sCCK-8 was unaffected by treatment with phentolamine, propranolol, guanethidine, atropine, hexamethonium or bilateral adrenalectomy. 6. The tetrapeptide of cholecystokinin (CCK-4) elicited a dose-dependent pressor response but did not induce bradycardia. The pressor response was unaffected by devazepide (50 nmol kg-1), L-365260 (15 mumol kg-1) or phentolamine (3 mumol kg-1). 7. In the pithed rat, sCCK-8 acted via CCKA receptors to increase arterial blood pressure indirectly, at least in part, through activation of alpha-adrenoceptors. The observed bradycardia was also mediated byCCKA receptors but possibly through a direct action on the heart.

Topics: Adrenalectomy; Adrenergic Agents; Animals; Benzodiazepinones; Blood Pressure; Bradycardia; Cholecystokinin; Decerebrate State; Devazepide; Dose-Response Relationship, Drug; Gastrins; Guanethidine; Heart Rate; Hormone Antagonists; Hormones; Hypertension; Indoles; Male; Meglumine; Pentagastrin; Phentolamine; Proglumide; Rats; Receptors, Cholecystokinin; Sincalide; Tetragastrin