Rethinking the new role of nasal epithel – more than a simple barrier?

It is important that the cell is able to transport molecules in and out of itself. The transport mechanisms can be divided in simple diffusion, facilitated diffusion, and active transport. Simple diffusion means that the molecules can pass directly through the membrane corresponding to a concentration gradient. Facilitated diffusion utilizes membrane protein channels to allow charged molecules to freely diffuse in and out of the cell. Active transport requires energy to transport the molecule from one side of the membrane to the other, but active transport is the only type of transport that can take molecules up their concentration gradient as well as down. Similarly to facilitated transport, active transport is limited by the number of protein transporters.

Drug transport through the nasal epithelium can be classified as either paracellular or transcellular. In the absence of active transport components, most drugs cross the nasal epithelium by the paracellular route, driven by passive diffusion. The transcellular route is relevant for carrier or receptor mediated transport processes or for transcytosis. Both transcellular routes are energy-dependent and are therefore designated as active transport processes. Additionally, the nasal epithelium is also rich in many cell-surface located enzymes. Apart from the “transport-barrier“ we have to consider the “metabolic barrier“. The “mucus barrier“ in the nasal epithelium is important for hydrophobic drugs, but relatively permeable to hydrophilic compounds.

Influence of various drugs on the ciliary beat activity has been investigated and the results will be presented. A separate lecture will deal with the highly important role of the immunologically active cells in the epithelium. An additional defence mechanism of the nasal mucosa will be discussed. The effects of herbal drugs on the immunological function of the epithelial cells will be revealed. Special interest has been focussed on the compartmentalisation of a herbal drug using high-sophisticated analytical methods.

Szelenyi I.: Transport mechanisms and function of nasal epithelial cells.

Stecher G.: What is to be found in different parts of the nasal epithelium? – Analytical profiles of a herbal drug.

Maune S.: Antibacterial activity of the nasal epithelium.

Neher A.: Influence of ciliary beating activity by different compounds.

Pahl A.: Is the nasal epithelium a simple barrier or an immunologically important organ?