Apparatus and methods for measuring smooth muscles responses (relaxation and contraction), transepithelial potential difference, and/or transepithelial impedance of an intact trachea in vitro. In particular embodiments, the apparatus includes a perfusion device on which an extracted, intact trachea is mounted. The perfusion device and the trachea are immersed in an extraluminal bath, which is isolated from the perfusion liquid flowing through the trachea. A set of voltage-sensing electrodes is provided for measuring the transepithelial potential difference across the trachea wall. A set of current electrodes is provided for inducing an electrical current to flow across the trachea wall in order to determine transepithelial impedance.