Rat airways express members of the Tas1R receptor family and several Tas2R bitter receptors. All of the Tas2R genes analyzed are expressed in the CV and Fol papillae, whereas only Tas2R105 and Tas2R134 are detected in the FF papillae. All tested Tas2Rs are detected in the nasal respiratory epithelium, larynx and trachea. With the exception of Tas2R13, all Tas2Rs are detected in the bronchi, but only Tas2R119 and Tas2R126 in the lung. None of the negative control tissue (heart, spleen and brain) showed any Tas2Rs or Tas1Rs expression. M = weight molecular marker; CV = circumvallate papillae; Fol = foliate papillae; FF = fungiform papillae; RE = respiratory epithelium; Lyx = larynx; Tra = trachea; Bro = bronchi; L = lung; Hea = heart; Spl = spleen; Br = brain.