Abstract: 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.

Abstract: 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.

Abstract: Specific method of irreversible antagonism of histamine receptors, especially H.sub.1 receptors, in, for example, isolated guinea pig vas deferens by 4(5)-[2-(4-azido-2-nitroanilino)ethyl]imidazole (AAH), which is a photoaffinity analog of histamine actuated unusually by light in the visible spectrum. Additionally, compounds of the present invention are represented by the formula ##STR1## wherein R.sub.1 and R.sub.2 represent an electron withdrawing group of the formula, H, --NO.sub.2, --Cl, --F, --Br, --I, --SO.sub.3 H. When two groups occur, it is not necessary that those groups be identical. In preferred compounds R.sub.1 is --NO.sub.2 and R.sub.2 is H and R.sub.1 is ortho to amine group.R.sub.3, R.sub.4, R.sub.5 and R.sub.6 represent a proton or lower alkyl of straight and branched carbon chains. In preferred compounds R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are protons or methyl groups with not more than two of the four positions substituted with an alkyl group. Preference is given for R.sub.4 and R.sub.5.