Cytokine-induced expression of the endothelial cell surface adhesion molecule E-selectin is inhibited by glucocorticoids (GCs). To investigate possible mechanisms for steroid inhibition, a reporter gene (ESAP) was constructed, comprising the cytokine responsive region of the E-selectin gene (nt -383 to +81) coupled to alkaline phosphatase (AP). In A549 cells stably transfected with the ESAP gene, AP production was highly responsive to the cytokines interleukin 1beta (IL-1beta) and tumour necrosis factor alpha, with ED50 values of 3 pM and 1000 pM respectively. Furthermore the cytokine-induced AP responses were inhibited by GCs, indicating that both transcriptional activation and GC suppression of the E-selectin gene were mediated via regulatory elements within the same region of the promoter. The relative potencies of GC drugs as inhibitors of IL-1beta (10 pM)-stimulated ESAP-gene activation were fluticasone> beclomethasone>dexamethasone, with IC50 values of 0.13, 1.1 and 2.7 nM respectively. Inhibition by fluticasone was blocked by the GC receptor (GR) antagonist drug mifepristone (Ru486), which is consistent with the suppressive effects of GCs being mediated via the GR. However, because the E-selectin promoter lacks a consensus glucocorticoid responsive element, mechanisms for inhibition independent of GR-DNA binding were investigated. Evidence that GCs also inhibited cytokine activation of a synthetic nuclear factor kappaB (NFkappaB)-driven reporter gene transiently transfected into A549 cells suggested that interference with the activation and/or function of this transcription factor was important for GC inhibition of ESAP. However, in A549-ESAP cells, fluticasone (100 nM) did not affect IL-1beta (10 pM)-induced IkBalpha degradation, NFkappaB-p65 nuclear translocation or the DNA-binding capacity of nuclear NFkappaB complexes, over a period during which cytokine-induced ESAP-gene activation was inhibited. Finally, there was no evidence to suggest that GC enhancement of IkBalpha gene expression contributed to the suppression of the cytokine response. We conclude that interference by GR with the transcriptional activation potential of DNA-bound NFkappaB complexes might contribute to mechanisms underlying the anti-inflammatory effects of GCs.

Summary1. Bronchodilator and cardiovascular actions of salbutamol and isoprenaline have been compared in guinea-pigs and dogs. Orciprenaline was also included in some experiments. 2. All three drugs antagonized acetylcholine-induced increases in pulmonary resistance. In addition they increased heart rate and decreased arterial blood pressure.3. Compared with isoprenaline, salbutamol has relatively stronger actions on bronchial and vascular /3-adrenoceptors than on cardiac 3-adrenoceptors, on which its action is very weak. In contrast, orciprenaline has similar potencies on 3-adrenoceptors in these three tissues. 4. The positive chronotropic potency of intravenously or orally administered salbutamol was increased in conscious dogs. These heart rate responses to salbutamol were probably mainly reflex in origin. 5. Salbutamol and orciprenaline were both longer acting than isoprenaline. 6. The results support the idea of two distinct groups of /3-adrenoceptors.Salbutamol differentiates between bronchial and vascular /32-adrenoceptors on the one hand and cardiac 831-adrenoceptors on the other. Isoprenaline and orciprenaline do not differentiate between f31-and f2-adrenoceptors.

IRanitidine has been investigated as an antagonist of the H2-receptor-mediated responses to histamine of guinea-pig atrium and rat uterus in vitro and as an inhibitor of gastric acid secretion in the rat.2 Ranitidine competitively antagonized histamine-induced increases in contraction frequency of the guinea-pig isolated right atrium. Ranitidine had a pA2 of 7.2 and was 7.9 and 4.5 times more potent than metiamide and cimetidine respectively. 3 Ranitidine competitively antagonized histamine-induced relaxations of the rat isolated uterine horn. Ranitidine had a pA2 of 6.95 and was 3.6 and 5.9 times more potent than metiamide and cimetidine respectively. 4 Ranitidine, even at high concentrations, did not affect responses of the guinea-pig isolated atrium or rat isolated uterus to (--isoprenaline. Similarly it was without effect on either histamine or bethanechol-induced contractions of guinea-pig isolated ileum. 5 Ranitidine inhibited histamine-and pentagastrin-induced gastric acid secretion in the perfused stomach preparation of the anaesthetized rat. Ranitidine was 5.2 and 7.0 times more potent on a molar basis than metiamide and cimetidine respectively, as an inhibitor of histamine-induced gastric acid secretion. 6 It is concluded that ranitidine is a potent, competitive and selective antagonist of histamine at H2-receptor sites and an effective inhibitor of gastric acid secretion in vivo.

SUMMARYThe new H2-receptor antagonist, ranitidine, has been compared with cimetidine and metiamide as an inhibitor of gastric acid secretion in the dog. All three compounds were effective both intravenously or by mouth in inhibiting secretion induced by histamine, pentagastrin, or bethanechol. This inhibition was mainly attributable to a reduction in the volume of secretion, although there was also a significant reduction in the concentration of acid secreted. Metiamide was slightly less active than cimetidine, but ranitidine was four to nine times more potent than cimetidine, depending on the secretagogue used. The antisecretory activity of ranitidine does not result from a limitation in blood flow to the gastric mucosa.It is now well established that the histamine H2-receptor antagonists metiamide and cimetidine inhibit gastric acid secretion in the dog12 and in man.34 Furthermore, cimetidine has proved to be highly effective in the treatment of duodenal ulcer.6 Both metiamide and cimetidine contain an imidazole ring which has been claimed to be an important feature for H2-receptor antagonist activity.6 However, a novel compound, ranitidine (AH 19065) has recently been described7 which lacks an imidazole ring (see Fig. 1), but possesses both potent H2-receptor antagonist and gastric antisecretory activity.The purpose of the present investigation was to compare the new H2-receptor antagonist ranitidine with metiamide and cimetidine as inhibitors of gastric acid secretion in the dog. The effects of the three H2-receptor antagonists have been studied in conscious dogs with Heidenhain pouches during stimulation of gastric acid secretion by three different secretagogues-histamine, pentagastrin and bethanechol. MethodsEight male beagles (13-19 kg) with well-established Heidenhain pouches were used, following the method previously described by Daly and Stables.8 Histamine, pentagastrin, or bethanechol was infused intravenously at a dose known to produce a 50%Received for publication 11 December 1979 AH 19065 Ranitidine maximal secretory response in each dog. The doses used were: histamine 0.3-0.5 gkg-'min-1, pentagastrin 1-4 gzg kg-' h,-' and bethanechol 0 5-1-0 ,ug kg-' min.-' Secretion from the Heidenhain pouch drained into a collection vessel which was changed every 15 minutes; the volume of secretion was measured to the nearest 0.1 ml and acid concentration determined by titration against 01 mol/l NaOH to pH7 with a Radiometer TTT2 titration system. Acid output was calculated in tumol H+/min.The secretory stimulant was infused continuously throughout the experiment. Once a plateau of gastric acid secretion had been obtained (less than 15% variation over one hour), a single dose of ranitidine, cimetidine or metiamide was administered as an intravenous bolus or by mouth in a capsule.The three H2-receptor antagonists were tested against each secretory stimulant over the following range of doses; ranitidine (0-03-1-0 mg/kg), cimetidine (01-3-0 mg/kg), and metiamide (0.3-3 0 mg/kg).In some of these experiments the...

I The potencies of fifteen /B-adrenoceptor agonists of widely differing chemical structures were compared with that of (-)-isoprenaline on bronchial muscle, soleus muscle, blood pressure and heart rate in the anaesthetized cat. The P-adrenoceptor antagonist potencies of propranolol and practolol were determined against (-)-isoprenaline in the same model. 2 (-)-Isoprenaline was the most potent agonist and its action was essentially unselective. Thus, on all four parameters the minimal effective dose was 0.003-0.01 .g/kg and maximal or near maximal responses were produced by 0.3-1 gg/kg. Trimetoquinol was also an essentially unselective agonist.3 For thirteen of the remaining fourteen agonists, potency was similar on bronchial muscle, soleus muscle and blood pressure but significantly lower on heart rate. 4 The remaining agonist AH 7616 (4-hydroxy-al-[[(1-methyl-3,3-diphenyl-propyl)aminolmethyll-m-xylene-al,a3-diol, acetate) -was also significantly less potent on heart rate than on the other parameters; in addition, it was clearly less potent on soleus muscle and blood pressure than on bronchial muscle when 5-hydroxytryptamine (5-HT) was used to induce bronchospasm. However, when acetylcholine was used instead of 5-HT the potency of AH 7616 on bronchial muscle, soleus muscle and blood pressure was very similar. AH 7616 may therefore possess a specific 5-HT antagonist action in addition to its,-adrenoceptor agonist action. 5The fifteen test agonists were longer acting than (-)-isoprenaline and this was particularly true of trimetoquinol and soterenol. 6 The /-adrenoceptor antagonist potency of propranolol was almost identical on bronchial muscle, soleus muscle and blood pressure and very slightly lower on the heart. Practolol was 10-12 times more potent on the heart than on bronchial muscle, soleus muscle and blood pressure. 7 These findings suggest that it may not be possible to separate the bronchodilating and tremorenhancing properties of /3-adrenoceptor agonists. The results with agonists and antagonists are in accord with Lands' dual /3-adrenoceptor sub-classification.