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Bacterial pneumonia stimulates macromolecule secretion and ion and water fluxes in sheep trachea
Abstract:
In vivo instillation of Pasteurella haemolytica (greater than or equal to 10(7) colony-forming units/kg) into a lobar bronchus of sheep produced bacterial pneumonia by 7 days postinoculation. Infection was verified bacteriologically and histologically. Macromolecule secretion and ion and water fluxes were subsequently measured in tracheal tissues in vitro and were compared with values from sham-infected sheep. Macromolecules were radiolabeled with 35SO4 and [3H]threonine, and we measured the secretion of macromolecule-bound radiolabel onto the mucosa. Unidirectional fluxes of Cl-, Na+, and water were measured with radioactive tracers under open-circuit and short-circuit conditions. Lung infection increased basal secretion of bound 35SO4 (by 189%) and bound [3H]-threonine (by 110%). It significantly increased net Na+ absorption under open- and short-circuit conditions and induced open-circuit net absorption of Cl- and water (16 +/- 29 microliters X cm-2 X h-1). These changes were associated with specific recruitment of neutrophils and elevated levels of arachidonate metabolites (thromboxane B2 and leukotriene B4) in the airways. Thus the bacterial pneumonia-induced changes in tracheal mucus secretion may be the result of airway inflammation.
Insights
Bacterial pneumonia in sheep significantly increased tracheal macromolecule secretion and ion/water transport. These changes, linked to airway inflammation, highlight mucus hypersecretion in lung infections.
Area of Science:
- Pulmonary Medicine
- Infectious Diseases
- Respiratory Physiology
Background:
- Bacterial pneumonia can alter respiratory tract function.
- Understanding mucus and ion transport changes is crucial for managing lung infections.
Purpose of the Study:
- To investigate the effects of Pasteurella haemolytica-induced pneumonia on ovine tracheal macromolecule secretion and ion/water transport.
- To correlate these physiological changes with airway inflammation markers.
Main Methods:
- Sheep were inoculated with Pasteurella haemolytica to induce pneumonia.
- Tracheal tissues were analyzed in vitro for macromolecule secretion (using 35SO4 and [3H]threonine) and ion (Cl-, Na+) and water fluxes.
- Neutrophil recruitment and arachidonate metabolite levels were assessed.
Main Results:
- Pneumonia significantly increased basal secretion of macromolecule-bound 35SO4 (189%) and [3H]threonine (110%).
- Net absorption of Na+ was significantly increased under both open- and short-circuit conditions.
- Open-circuit net absorption of Cl- and water was induced, associated with neutrophil influx and elevated thromboxane B2 and leukotriene B4.
Conclusions:
- Bacterial pneumonia alters tracheal macromolecule secretion and ion/water transport dynamics in sheep.
- These alterations are linked to airway inflammation, suggesting a role in mucus hypersecretion during lung infections.