TITLE:

ACTION POTENTIALS AS PROPAGATING DENSITY PULSES AND THE ROLE OF ANESTHETICS

DATE:

Friday, February 1st, 2008

TIME:

3:30 PM

LOCATION:

GMCS 214

SPEAKER:

Thomas Heimburg, Membrane Biophysics Group, Niels Bohr Institute, University of Copenhagen

ABSTRACT:

The action of nerves has been one of the first topics of interest in
biophysics. Important physicists like Galvani, Volta and Helmholtz were
among the first to study nerve pulse propagation. Nevertheless, there
still seems to be a communication barrier between molecular biology and
physics. Many models in biology contradict the intuition of a physicist
when it comes to the consideration of length and time scales, or to
the use and interpretation of physical variables. For the example of nerve
pulses and anesthesia it is shown that straightforward application of
thermodynamics may provide considerable insight into these seemingly
complicated processes.

Biological membranes display order transitions close to temperatures of
physiological interest. This feature leads to the possibility of
density pulse (soliton) propagation in such membranes. We discuss the
propagating pulses in the context of several striking properties of nerve membranes
under the influence of nerve pulses, including mechanical
dislocations and temperature changes. We relate it to the famous but so far unexplained
Meyer-Overton rule stating that the effectiveness of an anesthetic is
proportional to its membrane solubility. Anesthesia may find an
explanation in the well-known general phenomenon of freezing point
depression.

HOST:

Peter Salamon

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