Influence of anaesthetics on the melting transition of lipid membranes

The mechanism by which anaesthetics work is much discussed. The most prevalent view is that anaesthetics bind to ligand gated ion channels thereby restricting their function. Another view is that anaesthetics interact directly with the cell membrane, changing properties of the membrane leading to a conformational change in the membrane proteins which causes anaesthesia. In this thesis we will investigate the influence of general anaesthetics on the melting transition of artificial lipid membranes. This is done by calorimetry, pressure calorimetry and densitometry. We find that the melting transition broadens and the melting temperature is lowered when anaesthetics are added, and pressure shifts the melting point to a higher temperature. Furthermore the relation between volume change and enthalpy change is found. The work of this thesis was done in the Membrane Biophysics and Thermodynamics Group, Niels Bohr Institute, University of Copenhagen. The authors contributed equally to the project. The danish title is: Bedøvelsesmidlers indflydelse p̊a smelteovergangen i lipidmembraner. The picture on the front page is a schematic drawing of a biological membrane friendly provided by Thomas Heimburg. Anne Benedicte Mengel cpr.nr. 240383-1614 Maria Christiansen cpr.nr. 070682-2224