Pulmonary pharmacology
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Pulmonary pharmacology · Oct 1996
The role of capsaicin-sensitive C-fibre afferent nerves in the cough reflex.
While airway rapidly adapting receptors can mediate the cough reflex, much evidence suggests that bronchial C-fibre receptors are also involved in guinea-pigs and man. In man local and systemic C-fibre stimulants have a potent tussive action, which is blocked by low doses of local anaesthetics which leave the reflex bronchoconstriction intact. ⋯ Thus there may be subpopulations of airway C-fibres responsible for the different reflexes such as apnoea, cough and bronchoconstriction. The evidence for the role of C-fibre receptors in cough is described and discussed.
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Both human and animal studies show that irritation of airway mucosa elicits a variety of reflex responses such as coughing, apnoea, and laryngeal closure. Most of the information concerning these reflex responses were obtained in anesthetized conditions with little applicability to awake conditions. Various aspects of cough and other reflexes on irritation of the airway mucosa are discussed. ⋯ An increase in depth of anesthesia abolishes expiratory efforts such as coughing and the expiration reflex whereas the apnoeic reflex and laryngeal closure reflex are resistant to the depressant effect of anesthesia. Also, the respiratory reflex responses to airway irritation varied, depending on the site of stimulation: both laryngeal and tracheal stimulation cause vigorous respiratory responses whereas bronchial stimulation causes little or no respiratory responses. These results indicate not only that the types and magnitude of reflex responses is greatly modified by the central nervous state but also that the site of stimulation is crucial for determining the pattern of respiratory responses elicited by airway stimulation in humans.
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Pulmonary pharmacology · Feb 1996
Review Comparative StudyAirway sensory nerves in asthma--targets for therapy?
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Pulmonary pharmacology · Oct 1994
Effects of lung surfactant factor (LSF) treatment on gas exchange and histopathological changes in an animal model of adult respiratory distress syndrome (ARDS): comparison of recombinant LSF with bovine LSF.
Repetitive lung lavage of adult rats leads to lung injury similar to ARDS resulting in poor gas exchange, protein leakage and infiltration of polymorphonuclear neutrophils (PMN) into the alveolar spaces (J Appl Physiol 1983; 55: 131-138). In a previous dose response comparison we have demonstrated that poor gas exchange could be improved by lung surfactant factor (LSF) instillation soon after lavage. Since Surfacten (Tokyo Tanabe Co. ⋯ Inhibition of the inflammatory response (infiltration of PMN) was not effected by either of the LSF preparations at any dose level. The described variations in ventilator settings are useful to evaluate the deflation stability and re-expansion potential of different LSF preparations. The reported results give evidence that prevention of atelectasis by LSF treatment improves gas exchange and inhibits formation of hyaline membranes, leading to the conclusion that LSF treatment may be a promising therapy in ARDS patients.
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Pulmonary pharmacology · Dec 1993
Comparative Study Clinical TrialRandomized placebo-controlled study on the characteristics and duration of action of surfactant treatment in premature lambs.
In a placebo-controlled study, the characteristics and duration of action of a commercially available bovine lung surfactant factor (LSF; 50 mg/kg body weight) were investigated in premature lambs at 124-127 days gestational age. Exact mating of ewes was controlled by progesterone hormone analysis. To minimize unwanted effects of narcotics through transplacental transfer to the fetus, spinal anaesthesia of the ewes was performed. ⋯ Using a low respiratory rate it was possible to ventilate at lower peak inspiratory pressures and this resulted in higher compliance values. In conclusion, the presented data suggest that artificial ventilation greatly influences lung mechanics. Due to a relatively short substance effect concerning PaO2 we assume that higher or repeated doses of LSF may be necessary to produce sustained improvements in clinical trials.