Search results for "Histamine"

GABAergic inhibition of nitric oxide-mediated relaxation of guinea-pig ileum

1999

The effects of GABA receptor agonists were investigated on guinea-pig isolated ileum longitudinal muscle with intact myenteric plexus. Electrical field stimulation (1 Hz, 10 s) of the histamine (1 microM)-precontracted preparation caused a contraction followed by a relaxation. Relaxations were inhibited by L-N(G)-nitroarginine (L-NA; EC50 3 microM) in a concentration-dependent manner. The inhibitory action of 10 microM L-NA was blocked by 10 microM L-arginine but not by D-arginine, which indicates that the relaxation was largely mediated by endogenous nitric oxide (NO). Tetrodotoxin (1 microM) reduced the relaxation only by about 50%. GABA and the GABA(B) agonist, baclofen, inhibited the fi…

Pharmacological characterisation of a new model of antigen-induced pulmonary late-phase reaction in the conscious guinea pig which uses additional po…

1996

The aim of the present study was to develop a new model of allergic late-phase reaction in the airways of conscious guinea pigs (GPs) and to characterise it by pharmacological intervention. GPs were pretreated with cyclophosphamide and sensitized with ovalbumin (OA) in Al(OH)3. Weekly inhalations of polymyxin B were performed before and during sensitization and continued throughout the study period. Under cover of 10 mg/kg i.p. mepyramine all GPs still exhibited a pronounced immediate reaction (IR), peaking during the first 15 min after OA. Nine out of 15 GPs demonstrated, during screening, a reproducible (twice) second phase (late phase reaction (LPR)] of decreased airflow and tidal volume…

H2 antagonist and omeprazole nonresponders.

1991

A new 1-week therapy for Helicobacter pylori eradication: rani- tidine bismuth citrate plus two antibiotics

1997

Background: One-week triple regimens are currently the most recommended therapy for the eradication of Helicobacter pylori. No previous study has evaluated the efficacy of a short-term regimen combining ranitidine bismuth citrate with two antibiotics. Methods: Seventy-two consecutive H. pylori-positive dyspeptic patients were recruited for this randomized, three-centre, open, parallel-group study. They were subdivided into two groups receiving either ranitidine bismuth citrate 400 mg b.d. + clarithromycin 250 mg b.d. and metronidazole 500 mg b.d. (group A) or ranitidine bismuth citrate 400 mg b.d. + clarithromycin 250 mg b.d. and metronidazole 250 mg q.d.s (group B) for 1 week. H. pylori in…

EFFECTS OF VANADATE ON RESPONSES OF GUINEA-PIG ISOLATED TRACHEA TO SPASMOGENS

1993

Abstract The effects of vanadate on the contractility of the guinea-pig isolated trachea was examined. Vanadate (0·1 Mm) produced a sustained contraction that was abolished in Ca2+-free EGTA (0·1 Mm)-containing physiological salt solution but was resistant to verapamil (1 μm). Vanadate (0·1 Mm) depressed tracheal responses to CaCl2 (in Ca2+-free depolarizing solution), KCl, acetylcholine, histamine and 5-hydroxytryptamine. For vanadate (10 μm), the inhibition of spasmogenic responses only reached statistical significance for histamine and 5-hydroxytryptamine. Caffeine (1 Mm)-induced spasm (trachea at 20°C in the presence of indomethacin (2·8 μm)) was not affected by vanadate (10 μm-0·1 Mm).…

Involvement of prostaglandins and 5-hydroxytryptamine in the contractile effect of platelet-activating factor in rat isolated gastric corpus

1996

Abstract The present study characterizes the nature of the response to the platelet-activating factor (PAF) in isolated gastric corpus with and without mucosa. PAF (10-8 M) induced contraction of rat isolated gastric corpus strips followed by desensitization of this tissue. Incubation of strips with the specific PAF-receptor antagonist WEB 2086 (5 × 10-8 − 5 × 10-5 M), the prostaglandin blocker indomethacin (10-6 M) and the 5-hydroxytryptamine antagonist methysergide (10-5 M) reduced significantly the contraction induced by PAF. Neither of the histamine H1/H2 antagonists diphenhydramine (10-6 M) or cimetidine (10-5 M) affected the contraction induced by PAF. In contrast with the whole gastr…

EFFECTS OF PHORBOL 12,13-DIACETATE AND ITS INFLUENCE ON SPASMOGENIC RESPONSES IN NORMAL AND SENSITIZED GUINEA-PIG TRACHEA

1995

Abstract We have studied the effects of phorbol 12,13-diacetate (PDA) and its influence on a variety of spasmogenic responses in trachea isolated in from normal and sensitized guinea-pigs. Tracheal preparations were denuded of epithelium, treated with indomethacin (2·8 μm), and cooled to 20°C. In these experimental conditions, tracheal strips contracted to PDA (0·1 nm-1 μm). Contractions to PDA (1 μm) were greater in sensitized tissues. In normal trachea, contractions to PDA (0·1 μm) were depressed by H-7, 1-(5-isoquinolinyl-sulphonyl)-2-methylpiperazine, (50 μm), amiloride (10 μm), verapamil (10 μm) and Ca2+-free exposure. Similar effects were obtained in sensitized trachea except that PDA…

Clinic modelling randomised trials (CMRT's) in animals as a new intermediate between biological experiments and randomised clinical trials: applicati…

1998

Negative Effect of Ranitidine on The Results of Urea Breath Test for The Diagnosis of Helicobacter Pylori

2001

In analogy with proton pump inhibitors, H2-antagonists may also be responsible for false-negative results on urea breath test for the detection of Helicobacter pylori. In this study we assessed the frequency and duration of false-negative urea breath tests in patients given different doses of ranitidine.A total of 120 consecutive dyspeptic patients infected with H. pylori on the basis of concomitant positive results of CLO-test, histology and urea breath test were recruited for this prospective, open, parallel-group study performed in an urban university gastroenterological clinic. They were randomized to receive an acute treatment with either ranitidine 300 mg once a day in the evening, ra…

Histamine release in mesenteric traction syndrome during abdominal aortic aneurysm surgery: prophylaxis with H1 and H2 antihistamines

2002

Objective and design: Mesenteric traction syndrome is described as sudden tachycardia, hypotension and flush. Among other etiological factors eventeration or mesenteric traction of the small intestine may cause histamine release from mesenteric mast cells. We hypothesized that mesenteric traction syndrome may be positively influenced by prophylactic antihistamine administration.¶Methods: Male patients (n = 17, ASA groups III-IV, 48–78 years old) were investigated in a randomised double blind study during elective abdominal aortic aneurysm (AAA) repair. Eight patients had pre-anaesthetic prophylaxis with dimetindene (H1-receptor antagonist) plus cimetidine (H2-receptor antagonist), 9 patient…