The role of histamine H1 and H2 receptors in the lung is not clear. H1 receptor blockade results in bronchodilatation and inhibition of histamine induced bronchoconstriction. H2 receptor blockade in vitro prevents the normal negative feedback of histamine on further mediator release in antigen challenge. Bronchospasm in guinea pigs given antigen challenge is enhanced by previous administration ...

One of the common side effects of antihistamine medicines is xerostomia (dry mouth). The current consensus is that antihistamine-induced xerostomia comes from an antimuscarinic effect. Although the effect of antihistamines on salivary secretion is both obvious and significant, the cellular mechanism whereby this happens is still unclear because of the lack of knowledge of histamine signaling in...

Histamine is present in high concentrations in the intestine and we investigated the possibility that it might have a role here in intestinal transport. When added to the basal side of rabbit ileal mucosa in vitro histamine (10(-4)M) induced a short-lived increase in electrical potential difference and short circuit current. It inhibited net chloride absorption but did not influence sodium tran...

The main objective of this study was to investigate the ability of histamine receptor antagonists to modulate tryptase release from human colon mast cells induced by histamine. Enzymatically dispersed cells from human colon were challenged with histamine in the absence or presence of the histamine receptor antagonists, and the tryptase release was determined. It was found that histamine induced...

Competition experiments with [H]mepyramine showed that cetirizine and its enantiomers, levocetirizine and (S)-cetirizine, bound with high affinity and stereoselectivity to human H1 histamine receptors (Ki values of 6, 3, and 100 nM, respectively). Cetirizine and levocetirizine were 600-fold more selective for H1 receptors compared with a panel of receptors and channels. Binding results indicate...

Central histaminergic neurons have been implicated in the control of oxytocin (OT) secretion in various physiological conditions, including parturition and lactation. The present studies investigated whether histamine also influences the central intranuclear release of OT, which is known to be important in the activation of OT neurons, and the possible interaction of histamine with norepinephri...

Undifferentiated monolayers of the hamster vas deferens smooth-muscle cell line, DDT1MF-2, were grown on glass coverslips and loaded with the Ca(2+)-sensitive fluorescent dye fura-2. Stimulation with histamine produced a rapid and maintained increase in intracellular free Ca2+ ([Ca2+]i), with an EC50 of 7.0 +/- 0.7 microM. The initial rise in [Ca2+]i can be attributed to Ca2+ release from intra...

Abdominal ischemia stimulates sympathetic visceral afferents to reflexly activate the cardiovascular system. We have shown previously that topical application of histamine (HA) to the gastric wall causes reflex cardiovascular responses and have documented increased histamine concentrations in intestinal lymph and portal venous plasma during brief abdominal ischemia. In the present study, we hyp...

INTRODUCTION The neuroendocrine histamine-secreting cell of the gastric fundus, the enferochromaffin-like cell, is the principal regulator of parietal cell acid secretion. We have proposed that histamine may regulate its own synthesis and release via an autocrine mechanism. The purpose of this study was to evaluate the role of the histamine receptor subtypes H1, H2 and H3 in the regulation of t...