Articles: histamine.
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Pulm Pharmacol Ther · Jan 2005
Effect of histamine, albuterol and deep inspiration on airway and lung tissue mechanics in cynomolgus monkeys.
Forced oscillation is a technique that has been used to measure airway and lung tissue impedance. To evaluate airway and lung tissue impedance in a colony of cynomolgus monkeys housed at Schering-Plough Research Institute, a forced oscillation technique was used to measure Newtonian resistance (R(N)), tissue damping (G), tissue elastance (H) and lung hysteresivity (eta). Functional residual capacity (FRC) was also measured to correlate the lung impedance data with FRC. ⋯ Aerosolized albuterol (0.003-3mg/ml) produced a concentration-dependent reversal of the increases in R(N), G, H and eta induced by histamine with the greatest reversal seen on R(N). Deep inspiration, performed after the aerosolized albuterol exposure, also reversed the histamine-induced changes in R(N), G, and H with the complete reversal seen on the increase in H. These results demonstrate that significant correlations exist between airway and lung tissue impedance and FRC and that airway and lung tissue mechanics contribute significantly to inherent bronchoconstrictor reactivity and to the bronchodilator response to a beta-adrenergic agonist and deep inspiration in cynomolgus monkeys.
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Extensive evidence suggests that histaminergic neurons promote wakefulness. Histaminergic neurons are found exclusively in the tuberomammillary nucleus (TMN), and electrolytic lesions of the posterior hypothalamus, where the TMN resides, produce intense hypersomnolence. However, electrolytic lesions disrupt fibers of passage, and the effects of fiber-sparing, cell-specific TMN lesions on sleep and wakefulness are unknown. Hence, we placed cell-specific lesions in the TMN to determine its role in spontaneous wakefulness. ⋯ The absence of gross changes in sleep after extensive loss of histaminergic neurons suggests that this system is not critical for spontaneous wakefulness.
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Anesthesia and analgesia · Jun 2004
Randomized Controlled Trial Comparative Study Clinical TrialMethadone for the induction of anesthesia: plasma histamine concentration, arterial blood pressure, and heart rate.
Despite the widespread use of methadone for the treatment of acute and chronic pain, the hemodynamic effects of methadone administered by IV bolus have not been studied. We compared the hemodynamic effects of an IV bolus of methadone 20 mg with those of fentanyl 10 microg/kg for the induction of anesthesia in combination with etomidate 0.3 mg/kg. Forty-three patients undergoing major surgery were randomized to one of the two treatments in a double-blinded fashion. Plasma concentrations of histamine were measured before and 2 min after opioid administration. Heart rate and arterial blood pressure were measured via an arterial line just before opioid administration, etomidate administration, and tracheal intubation; during intubation; and 1 min after intubation. There were no significant differences in mean heart rate between the methadone and fentanyl groups at any time point. Systolic and diastolic blood pressures were significantly lower (P < 0.05) in the fentanyl group just before intubation, during intubation, and 1 min after intubation. Mean plasma concentrations of histamine before and after the administration of methadone or fentanyl were 1.54 ng/mL (SD, 0.65 ng/mL) and 1.57 ng/mL (SD, 1.37 ng/mL) or 1.00 ng/mL (SD, 0.58 ng/mL) and 1.04 ng/mL (SD, 0.47 ng/mL), respectively. Despite the lack of a significant change in mean plasma concentrations of histamine, substantial increases in plasma histamine occurred in 2 of 23 patients who received methadone. There were no obvious hemodynamic effects associated with histamine concentrations up to 6.2 ng/mL. Methadone appears to have the potential for producing histamine release. Although methadone administration did not produce hemodynamic instability in this study, the possible hemodynamic side effects of histamine release should be considered when IV boluses of methadone are given. ⋯ The same dose of IV methadone (20 mg) that is effective for postoperative pain is also suitable for the induction of anesthesia in combination with etomidate. The plasma histamine concentration was notably increased in two patients, without obvious hemodynamic sequelae. Therefore, methadone appears to have the potential for producing histamine release.
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Comparative Study
Neuronal sensitization for histamine-induced itch in lesional skin of patients with atopic dermatitis.
Lowered threshold of neurons (ie, neuronal sensitization) in atopic dermatitis was investigated by testing sensitivity to histamine. ⋯ As the area of axon reflex flare is an indirect measure of activity in primary afferent neurons, our results suggest a decreased activation of peripheral pruriceptors in patients with AD. The massively increased itch in lesional skin of patients with AD might therefore be based on sensitization for itch in the spinal cord rather than in primary afferent neurons. This sensitization does not appear to be simply based on skin inflammation because histamine-induced itch was not augmented in lesional skin of psoriasis.
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Comparative Study
Histaminergic facilitation of electrocorticographic activation: role of basal forebrain, thalamus, and neocortex.
The neuromodulator histamine plays an important role in the regulation of behavioural state and the neocortical electrocorticogram (ECoG). With the present experiments, we characterized the anatomical targets that mediate the cortical-activating effects of histamine. Urethane-anaesthetized rats displayed continuous large-amplitude, low-frequency oscillations with a maximal spectral power in the delta (0.5-3.9 Hz) frequency band. ⋯ These data suggest that, under the present experimental conditions, histamine facilitates ECoG activation primarily by potentiating the excitatory influence of brainstem fibers at the level of the basal forebrain. Histamine release in some parts of the thalamus results in a minor enhancement of ECoG activation, and cortical histamine release produces a small but consistent suppression of slow delta oscillations in the resting ECoG. These concurrent subcortical and cortical actions probably permit histamine to effectively modulate cortical activation and excitability across different behavioural states.