Actin-ATP Hydrolysis Is a Major Energy Drain for Neurons

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Abstract
In cultured chick ciliary neurons, when ATP synthesis is inhibited, ATP depletion is reduced ∼50% by slowing actin filament turnover with jasplakinolide or latrunculin A. Jasplakinolide inhibits actin disassembly, and latrunculin A prevents actin assembly by sequestering actin monomers. Cytochalasin D, which allows assembly–disassembly, but only at pointed ends, is less effective in conserving ATP. Ouabain, an Na+–K+-ATPase inhibitor, and jasplakinolide both prevent ∼50% of the ATP loss. When applied together, they completely prevent ATP loss over a period of 20 min, suggesting that filament stabilization reduces ATP consumption by decreasing actin-ATP hydrolysis directly rather than indirectly by modulating the activity of Na+–K+-ATPase, a major energy consumer.