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Published on: January 16, 2015
Sidestream smoke effects on lung morphology and C-fibers in young guinea pigs
J P Joad1, J M Bric, K E Pinkerton
1Department of Pediatrics, School of Medicine, University of California at Davis 95616, USA.
Insights
Secondhand smoke exposure in young guinea pigs impaired their pulmonary defense system, potentially affecting children exposed to smoking in homes. This highlights risks to respiratory health from environmental tobacco smoke.
Area of Science:
- Environmental Health
- Pulmonary Physiology
- Toxicology
Background:
- Children exposed to environmental tobacco smoke exhibit respiratory issues.
- Sidestream smoke (SS) is a major component of secondhand smoke.
- The impact of SS on developing lung defense mechanisms is not fully understood.
Purpose of the Study:
- To investigate the effects of chronic sidestream smoke exposure on lung function and morphology in developing guinea pigs.
- To assess changes in the bronchopulmonary C-fiber system's activity following SS exposure.
Main Methods:
- Developing guinea pigs were exposed to filtered air (FA) or SS for 6 hours/day, 5 days/week, from 8 to 43 days of life.
- Lung function was assessed using an isolated buffer-perfused system.
- Reactivity to capsaicin (C-fiber stimulant) and substance P (SP) was measured.
Main Results:
- SS exposure increased baseline dynamic compliance (Cdyn) by 17% but did not alter pulmonary resistance (RL).
- SS exposure reduced the airway response to capsaicin but not to substance P.
- Lung morphology, including alveolar size and elastin deposition, remained unchanged.
Conclusions:
- Chronic SS exposure in developing guinea pigs alters lung mechanics and diminishes C-fiber mediated airway responses.
- These findings suggest that children exposed to secondhand smoke may have a compromised pulmonary defense system.
Abstract:
Children raised in homes with smokers have more frequent respiratory symptoms, decreased lung function, and increased airway reactivity. This study was designed to evaluate whether chronic exposure of developing guinea pigs to sidestream smoke (SS) would impair lung function and morphology and/or change the activity of a pulmonary defense mechanism, the local bronchopulmonary C-fiber system. Duncan-Hartley guinea pigs (n = 29) were exposed to filtered air (FA) or to SS for 6 h/day, 5 days/week from 8 to about 43 days of life. Their lungs were then studied in an isolated buffer perfused system where increasing doses of capsaicin (a C-fiber stimulant) or substance P (SP, a C-fiber neurotransmitter) were injected into the pulmonary artery. SS exposure significantly increased baseline dynamic compliance (Cdyn) by 17% but did not change baseline pulmonary resistance (RL). SS exposure reduced the capsaicin-induced change in RL and Cdyn but did not change lung responsiveness to SP. SS exposure did not change fixed lung volume, surface area, mean linear intercept length, or elastin deposition. We conclude that SS exposure to developing guinea pigs (1) increased lung compliance without affecting alveolar size or elastin deposition and (2) decreased the airway reactivity of the C-fiber system without changing reactivity to one of its neurotransmitters, SP. If humans are similarly affected, children raised in the homes of smokers may have a diminished pulmonary defense mechanism.
