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Table 1 Properties of low threshold mechanosensor subtypes innervating the guinea pig airways.

From: An overview of the sensory receptors regulating cough

  SAR RAR Cough Receptor
Anatomical Characteristics:    
Ganglionic Origin Nodose Nodose Nodose
Extrapulmonary Termination No No Yes
Intrapulmonary Termination Yes Yes Few
Substance P Expression No No No
TRPV1 Expression No No No
Functional Characteristics:    
Conduction Velocity (m/sec) ~18 (Aβ) ~15 (Aβ) ~5 (Aδ)
Mechanical Threshold Low Low Low
Sensitive to:    
   Punctate Mechanical Yes Yes Yes
   Capsaicin Yes1 Yes1 No
   Hypertonic Saline Unknown Unknown Yes
   Bradykinin Yes1 Yes1 No
   Acid No Unknown Yes
   Inflation (≤50 cmH 2 O) Yes Yes No
   Deflation/Collapse No Yes No
   Stretch Yes Yes No
   Bronchoconstriction Yes Yes No
   ATP Yes Yes No
Reflex Effects on Respiration Hering-Breuer Tachypnea Cough
  1. 1 SARs and RARs are insensitive to the direct action of these chemicals on the nerve terminal. However, chemical stimuli such as capsaicin and bradykinin can activate SARs and RARs secondary to airway smooth muscle contraction, mucous secretion or edema formation. Cough receptors are insensitive to both the direct and indirect actions of capsaicin and bradykinin. See text for references.