The Department of Biomedicine

BBB seminar: Thomas Heimburg

The action potential and the role of anesthetics: A lipid membrane view

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Thomas Heimburg
Niels Bohr Institute, University of Copenhagen, Denmark

The lipids of biological membranes display chain-melting transitions close to temperatures of physiological interest. During this transition the heat capacity, volume and area compressibilities all reach maxima and domains form. We show that this feature leads to the possibility of density pulse propagation in such membranes. In particular, if the membrane state is above the melting transition, the pulses will involve changes in lipid state. We discuss the propagating pulses in the context of several striking properties of nerve membranes under the influence of the action potential, including mechanical dislocations and temperature changes. On the basis of the thermal properties of nerves we want to explain the influence of anesthetics on the threshold of nerve pulse excitation. We relate it to the famous but so far unexplained Meyer-Overton rule stating that the effectiveness of an anesthetic is closely linked to its membrane solubility.

Host: Holm Holmsen, Department of Biomedicine

Thomas Heimburg

Thomas Heimburg was born in London in 1960. He received his PhD in Biophysics and Physical Chemistry (thesis on ” Biophysics of membrane transitions ”) from the University of Göttingen, Germany, in 1989. After having held several research appointments (University of Virginia, Charlottesville , USA; Ma x Planck Institute for Biophysical Chemistry, Göttingen; McGill University, Montréal, Canada; Technical University in Lyngby, Denmark ), Thomas is now Associate Professor at the Niels Bohr Institute at the University of Copenhagen. His general interest is in biophysics of biomembranes and his talk will focus on the propagation of density pulses ( solitons) in nerves.

Homepage: http://membranes.nbi.dk