The effects of both an H1 receptor antagonist and an H2 receptor antagonist on changes in monovalent ion flux induced by topical sodium taurocholate were studied in antrectomised dogs fashioned with a denervated fundic pouch. The magnitude of taurocholate-induced ion flux was unaffected by topical administration of H1 or H2 receptor antagonists Parenteral administration of H1 or H2 receptor ant...

We used television microscopy and an image-splitting technique to monitor the changes in diameter produced by histamine applied locally to mouse pial arterioles in vivo. A high dose (50 micrograms/ml, 3 X 10(-4) M) of histamine constricted the arterioles, whereas lower doses (20 and 10 micrograms/ml) relaxed them. Constriction was blocked and dilation occurred when selective injury of the endot...

H1 and H2 histamine receptor antagonists, although developed many decades ago, are still effective for the treatment of allergic and gastric acid-related conditions. This article focuses on novel aspects of the pharmacology and molecular mechanisms of histamine receptors that should be contemplated for optimizing current therapies, repositioning histaminergic ligands for new therapeutic uses, o...

Histamine causes vasodilation in the dog by activation of H1 and H2 receptors blocked by mepyramine and metiamide, respectively. Experiments were conducted in anesthetized dogs to determine the participation of H1 and H2 receptors in several forms of physiological dilatation. Mepyramine attenuated both histamine-induced and active-reflex dilatation in the hindlimb. Metiamide caused a further re...

restraint-induced stress (rs) increases histamine concentration in the brain. there is no previous report regarding the role of histamine receptors in immunomodulatory effect of rs. in the present study the role of brain histamine receptors on reduction of humoral and cellular immune function induced by rs was evaluated. for this purpose male wistar rats (200-250 g) were immunized with sheep re...

The histamine H4 receptor is a novel G-protein-coupled receptor with a unique pharmacological profile. The distribution of H4 mRNA suggests that it may play a role in the regulation of immune function, particularly with respect to allergy and asthma. To define the histamine-binding site of this receptor, molecular modeling and site-directed mutagenesis were used to predict and alter amino acids...

The effects of microinjection of histamine into the paraventricular nucleus (PVN) of the hypothalamus on yawning responses were investigated in anesthetized, spontaneously breathing rats. Yawning responses were evaluated by monitoring the intercostal electromyogram (EMG) as an index of inspiratory activity and digastric EMG as an indicator of mouth opening. We also recorded the electrocorticogr...

Several lines of evidence suggest that brain histamine may be involved in the central control of food intake. The effect of histamine on feeding is mediated through three kinds of receptors (H1, H2, and H3). The present study was designed to investigate the effect of intracerebroventricular injection of histamine, promethazine (H1 antagonist) and ranitidine (H2 antagonist) on food intake of fre...

Histamine affects pancreatic secretion, but its direct action on ion transport by pancreatic duct epithelial cells (PDEC) has not been defined. We now characterize the secretory effects of histamine on cultured, well-differentiated, and nontransformed dog PDEC. Histamine stimulated, in a concentration-dependent manner (1-100 μM), a cellular125I-efflux that was inhibited by 500 μM 5-nitro-2-(3-p...