Afferent vagal pathways mediating respiratory reflexes evoked by ROS in the lungs of anesthetized rats

• Published in: Journal of applied physiology (1985) Vol. 94; no. 5; pp. 1987 - 1998
• Main Authors: Ruan, Ting, Ho, Ching-Yin, Kou, Yu Ru
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01-05-2003; American Physiological Society
• Subjects: Aerosols; Animals; Antioxidants - pharmacology; Biological and medical sciences; Blood Pressure - drug effects; Capsaicin - pharmacology; Cardiorespiratory control. Arterial mecano- and chemoreceptor; Catalase - pharmacology; Dose-Response Relationship, Drug; Female; Fundamental and applied biological sciences. Psychology; Hydrogen Peroxide - pharmacology; In Vitro Techniques; Lung - drug effects; Lung - innervation; Lungs; Male; Nerve Fibers, Unmyelinated - drug effects; Nerve Fibers, Unmyelinated - physiology; Nervous system; Neural Pathways - drug effects; Neural Pathways - physiology; Neurons, Afferent - drug effects; Neurons, Afferent - physiology; Oxidants - pharmacology; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species - pharmacology; Reflexes; Respiratory Mechanics - drug effects; Respiratory system; Rodents; Stimulation, Chemical; Tidal Volume; Vagus Nerve - cytology; Vagus Nerve - drug effects; Vagus Nerve - physiology; Vertebrates: respiratory system; Reflex; Oxygen; Rat; Rodentia; hydrogen peroxide; Sensory receptor; oxygen radicals; Hydrogen Peroxides; Free radical; Inhalation; Dose activity relation; vagal sensory receptors; Vertebrata; Mammalia; Ventilatory response; reactive oxygen species; Afferent projection; Vagus nerve; Respiratory control; Respiration
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.01047.2002

1  Institute of Physiology, School of Medicine,
National Yang-Ming University, and 2  Department of
Otolaryngology, Taipei Veterans General Hospital, Taipei 112, Taiwan
We investigated the afferent
vagal pathways mediating respiratory reflexes evoked by reactive oxygen
species (ROS) in the lungs of anesthetized rats. Spontaneous
inhalation of 0.2% aerosolized H 2 O 2 acutely
evoked initial bradypnea followed by delayed tachypnea, which was
frequently mixed with delayed augmented inspiration. The initial
response was abolished after perivagal capsaicin treatment (PCT), but
was prolonged during vagal cooling (VC) to 7°C; PCT and VC are known
to differentially block the conduction of unmyelinated C and myelinated
fibers, respectively. The delayed responses were eliminated during VC
but emerged earlier after PCT. Vagotomy, catalase (an antioxidant for
H 2 O 2 ), dimethylthiourea (an antioxidant for
· OH), or deferoxamine (an antioxidant for · OH) largely or totally suppressed these reflexive responses, whereas sham nerve treatment, heat-inactivated catalase, saline vehicle, or iron-saturated deferoxamine failed to do so. These results suggest that 1 )
the H 2 O 2 -evoked initial and delayed airway
reflexes are antagonistic and may result from stimulation of lung C
fibers and rapidly adapting receptors, respectively, and 2 )
the reflex effects of H 2 O 2 are, in part, due to
the action of · OH on these afferents.
vagal sensory receptors; oxygen radicals; reactive oxygen species; hydrogen peroxide