Pyrilamine (mepyramine) is an H1-receptor antagonist used in human and veterinary medicine. It has the potential to produce central nervous system effects in horses and therefore may have some impact on an outcome of a horse race. A single oral dose of pyrilamine (300 mg/horse) was given to three animals. Serum samples were collected before drug administration and at 0.25, 0.5, 1, 2, 4, 6, 24, ...

We have demonstrated previously the importance of histaminergic neurons in arousal mechanisms. In addition to their ascending axons, these neurons also send heavy descending inputs to the mesopontine tegmentum (MPT), which plays a key role in cortical activation during wakefulness (W). This anatomical link suggests histaminergic control of the mechanisms of the MPT relevant to behavioral states...

has postulated that iron deficiency may be a cause of gastritis and gastric secretory failure as well as of other epithelial changes, such as glossitis and pharyngitis. The return of gastric acidity after iron-deficiency anaemia had been cured was reported on several occasions at a time when test meals or small doses of histamine were used to The introduction of maximal histamine stimulation (K...

Histamine is a known secretagogue in adrenal chromaffin cells. Activation of G-protein linked H(1) receptors stimulates phospholipase C, which generates inositol trisphosphate leading to release of intracellular calcium stores and stimulation of calcium influx through store operated and other channels. This calcium leads to the release of catecholamines. In chromaffin cells, the main physiologi...

Nociceptin/orphanin FQ (N/OFQ) is the endogenous ligand for the N/OFQ peptide receptor (NOP). N/OFQ causes hypotension and vasodilation, and we aimed to determine the role of histamine in inflammatory microvascular responses to N/OFQ. Male Wistar rats (220-300 g, n = 72) were anesthetized with thiopental (30 mg/kg bolus, 40-90 mg x kg(-1) x h(-1) iv), and the mesentery was prepared for fluoresc...

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...

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...

It has long been recognized that comparatively few cases of nephritis in childhood die in the early stages of the disease and it is widely believed that the great majority of cases recover completely. Hebert (1952) has summarized the results of many of the long-term studies of nephritis in childhood published in the British and American literature in the past 30 years. In the majority of these ...

To indentify the histamine-receptors in the canine myocardium, experiments were performed in the canine heart-lung preparation supported by a donor. Smaller doses of histamine produced only an increase in the coronary blood flow. Positive inotropic and chronotropic effects appeared with larger doses. The increase in the coronary blood flow was associated with only a minimal increase in the myoc...

1. Inhalation of vanadium compounds, particularly vanadate, is a cause of occupational bronchial asthma. We have now studied the action of vanadate on human isolated bronchus. Vanadate (0.1 microM-3 mM) produced concentration-dependent, well-sustained contraction. Its -logEC50 was 3.74 +/- 0.05 (mean +/- s.e.mean) and its maximal effect was equivalent to 97.5 +/- 4.2% of the response to acetylc...