title: Exciting cell membranes with a blustering heat shock.
abstract: Brief heat shocks delivered to cells by pulsed laser light can evoke action potentials in neurons and contraction in cardiomyocytes, but the primary biophysical mechanism has been elusive. In this report we show in the neuromuscular junction of Caenorhabditis elegans that application of a 500°C/s heat shock for 500 μs evoked ~35 pA of excitatory current and injected ~23 fC(femtocoulomb) of charge into the cell while raising the temperature only 0.25°C. The key variable driving the current was the rate of change of temperature (dT/dt heat shock), not temperature itself. The photothermal heat shock current was voltage-dependent and was from thermally driven displacement of ions near the plasma membrane. The charge movement was rapid during the heat shock and slow during thermal relaxation, thus leading to an asymmetrical capacitive current that briefly depolarized the cell. A simple quantitative model is introduced to describe modulation of the membrane potential and facilitate practical application of optical heat shock stimuli.
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, Utah.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Department of Bioengineering, University of Utah, Salt Lake City, Utah.
authors.forename: Micah J
authors.initials: MJ
authors.lastname: Frerck
authors.affiliation: Department of Bioengineering, University of Utah, Salt Lake City, Utah.
authors.forename: Holly A
authors.initials: HA
authors.lastname: Holman
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, Utah; Howard Hughes Medical Institute, University of Utah, Salt Lake City, Utah.
authors.forename: Erik M
authors.initials: EM
authors.lastname: Jorgensen
authors.affiliation: Department of Bioengineering, University of Utah, Salt Lake City, Utah; Marine Biological Laboratory, Woods Hole, Massachusetts. Electronic address: r.rabbitt@utah.edu.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Rabbitt
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000378:metabolism / Q000502:physiology*; D002462:Cell Membrane / Q000502:physiology*; D018869:Heat-Shock Response; D007259:Infrared Rays; D009154:Mutation / Q000235:genetics; D018408:Patch-Clamp Techniques; D013696:Temperature
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