Histamine and carbachol contractile responses in proximal and distal airways of the rabbit

Airway preparations from the trachea, main bronchi, subsegmental bronchi and the parenchyma of rabbits were studied. The proximal airways, the trachea and main bronchi, were less sensitive to histamine than the distal airways of the subsegmental bronchi and lung parenchymal strip. The proximal airways were more sensitive to carbachol than the distal airways. These results may assist in the interpretation of airway responses in vivo.