Articles: histamine.
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of the effects of desloratadine and levocetirizine on histamine-induced wheal, flare and itch in human skin.
A previous study showed the inhibitory effects of loratadine on histamine-induced wheal, flare and itch in human skin to be very variable between individuals. It was hypothesised that this variability may have been due to differences in the rates of metabolism of loratadine to its active form, desloratadine. This double blind, crossover study examined the effects of desloratadine in 12 healthy volunteers. Levocetirizine was used as a comparator. ⋯ A single dose of 5 mg levocetirizine produced more consistent and greater inhibitory effects on histamine-induced wheal, flare and itch than did 5 mg desloratadine. The difference is suggested to reflect the basic pharmacokinetics of the two drugs.
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J. Pharmacol. Exp. Ther. · Oct 2003
Contractions to histamine in pulmonary and mesenteric arteries from endotoxemic rabbits: modulation by vascular expressions of inducible nitric-oxide synthase and histamine H1-receptors.
The inducible isoform of nitric-oxide synthase (iNOS) is highly expressed after induction of endotoxemia and contributes to vascular hypocontractility in endotoxemia. Circulating levels of histamine are elevated in animal models of sepsis and in patients with septic shock. This study assessed whether the vascular effects of histamine play a significant role in the pathophysiology of endotoxemic shock despite the hyporesponsiveness to vasoconstrictors associated with iNOS up-regulation. ⋯ This was possibly associated with a dramatic increase in H1-receptor expression at the gene and protein levels, as determined by Northern blot and immunoblot analyses. Furthermore, we found that LPS-induced endotoxemia caused prominent increases in production of histamine through induction of histidine decarboxylase in tissues, including blood vessels. From these results, we propose that histamine may contribute to the development of endotoxin-induced pulmonary hypertension.
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J. Allergy Clin. Immunol. · Oct 2003
Letter Case ReportsHistamine inhalation challenge in recurrent uvula angioedema.
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Comparative Study
Waking selective neurons in the posterior hypothalamus and their response to histamine H3-receptor ligands: an electrophysiological study in freely moving cats.
Neurons which discharge selectively during waking (waking selective) have been found in the tuberomamillary nucleus (TM) and adjacent areas of the posterior hypothalamus. Although they share some electrophysiological properties with aminergic neurons, there is no direct evidence that they are histaminergic. We have recorded from posterior hypothalamic neurons during the sleep-wake cycle in freely moving cats, and investigated the effects on waking selective neurons of specific ligands of histaminergic H3-receptors, which autoregulate the activity of histaminergic neurons. ⋯ Moreover, the effect of the antagonist was reversed by the agonists and vice versa. In contrast, "waking-related" neurons were unaffected by these H3-receptor ligands. These data provide evidence for the histaminergic nature of "W-on" neurons and their role in cortical desynchronization during waking, and highlight the heterogeneity of posterior hypothalamic neuronal populations, which might serve different functions during the wakefulness.
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Pediatr Crit Care Me · Jul 2003
Bradykinin and histamine generation with generalized enhancement of microvascular permeability in neonates, infants, and children undergoing cardiopulmonary bypass surgery.
To investigate whether generation and liberation of bradykinin and histamine contribute to generalized edema formation in pediatric cardiopulmonary bypass surgery. ⋯ Bradykinin seems to be essentially involved in the enhancement of microvascular permeability in pediatric cardiopulmonary bypass surgery, although a dominant causal role cannot be claimed by this study. Histamine, however, doesn't appear to play a major role and may only contribute as a cofactor. To what extent an increased expression of bradykinin-1 and bradykinin-2 receptors or a reduced potential of bradykinin-degrading enzymes is involved is the object of a further clinical study.