Local vagal responses in the lung periphery.

Area of Science:

• Pulmonary physiology
• Respiratory system responses
• Toxicology

Background:

• Previous studies demonstrated ozone (O3) exposure in the lung periphery increases collateral resistance (Rcs).
• These O3-induced responses were found to be vagally mediated, as vagotomy or atropine prevented them.

Purpose of the Study:

• To investigate if the vagus nerve is essential for O3 responses by maintaining baseline tone.
• To determine if physiological responses to localized O3 exposure are confined to the challenged lung region.

Main Methods:

• Dogs were exposed to 0.1 ppm O3 via a bronchoscope.
• Baseline Rcs was increased using neostigmine (an acetylcholinesterase inhibitor).
• O3 exposure was administered to single or multiple lung regions using one or two bronchoscopes.

Main Results:

• Increased baseline Rcs with neostigmine potentiated O3-induced Rcs increase only when vagi were intact.
• Localized O3 exposure resulted in responses only in the challenged region.
• Widespread O3 exposure led to responses in both lungs, but only if vagi were intact.

Conclusions:

• The lung can mount vagally mediated responses to localized oxidant injury, confined to the exposed area.
• When oxidant insult affects a larger lung area, vagally mediated responses become generalized, impacting both lungs.