Diverse molecules induce general anesthesia with potency strongly correlated both with their hydrophobicity and their effects on certain ion channels. We recently observed that several  anesthetics inhibit heterogeneity in plasma membrane derived vesicles by lowering the critical temperature (T_c) for phase separation. Here we exploit conditions that stabilize membrane heterogeneity to  test the correlation between the anesthetic potency of n-alcohols and effects on T_c. First we show that hexadecanol acts oppositely to  anesthetics on membrane mixing and antagonizes ethanol induced anesthesia in a tadpole behavioral assay. Second, we show that two previously described `intoxication reversers' raise T_c in vesicles and counter ethanol's effects in vesicles, mimicking the findings of previous electrophysiological  measurements. Third, we find that hydrostatic pressure, long known to reverse anesthesia, also raises T_c in vesicles with a magnitude that counters the effect of an anesthetic at relevant concentrations and pressures. Taken togetner , these results demonstrate that \Delta T_c predicts anesthetic potency for n-alcohols better than hydrophobicity in a range of contexts, supporting a mechanistic role for membrane heterogeneity in general anesthesia.
Diverse molecules induce general anesthesia with potency strongly correlated both with their hydrophobicity and their effects on certain ion channels. We recently observed that several n-alcohol anesthetics inhibit heterogeneity in plasma membrane derived vesicles by lowering the critical temperature (T_c) for phase separation. Here we exploit conditions that stabilize membrane heterogeneity to further test the correlation between the anesthetic potency of n-alcohols and effects on T_c. First we show that hexadecanol acts oppositely to n-alcohol anesthetics on membrane mixing and antagonizes ethanol induced anesthesia in a tadpole behavioral assay. Second, we show that two previously described `intoxication reversers' raise T_c and counter ethanol's effects in vesicles, mimicking the findings of previous electrophysiological and behavioral measurements. Third, we find that hydrostatic pressure, long known to reverse anesthesia, also raises T_c in vesicles with a magnitude that counters the effect of butanol at relevant concentrations and pressures. Taken together , these results demonstrate that \Delta T_c predicts anesthetic potency for n-alcohols better than hydrophobicity in a range of contexts, supporting a mechanistic role for membrane heterogeneity in general anesthesia.
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n-alcohol
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further
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n-alcohol
D
in vesicles
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and behavioral
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an anesthetic
butanol
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togetner
together