Alteration of synaptic membrane fatty acid composition and anesthetic requirement.

Mice fed a saturated, Purina chow or unsaturated fat diet from birth have different synaptic membrane fatty acid compositions. The saturated diet decreased docosahexaenoic [22:6 (n - 3)] and increased eicosatrienoic [20:3 (n - 9)], docosatrienoic [22:3 (n - 9)] and docosapentaenoic [22:5 (n - 6)] fatty acids compared to the Purina chow or unsaturated fat diet. The most notable alterations occurred in the synaptic membrane phosphatidylserine and phosphatidylethanolamine fractions. The saturated diet also caused a minor increase in oleic acid [18:1 (n - 9)i1. Animals fed the saturated diet showed a small, significant decrease in nitrous oxide ED50 (dose required to abolish the righting reflex in half the animals) but not in isoflurane ED50, compared to animals fed the Purina chow or unsaturated fat diet. Thus, large alterations in several synaptic membrane fatty acid components have little or no influence on anesthetic requirement.