2,3-Butanedione 2-Monoxime

2,3-Butanedione 2-Monoxime is a skeletal and cardiac muscle contraction inhibitor. Broad reversible inhibitor of myosin ATPase in eukaryotes. Shown to induce Ca²⁺ release from canine cardiac SR. KV2.1 current was inhibited at all potentials; the time course of current activation, deactivation and inactivation were unaffected by 2,3-Butanedione monoxime. In inside-out patch-clamp experiments, the application of 2,3-Butanedione monoxime to the cytoplasmic surface similarly inhibited channel activity rapidly and reversibly (K_i = 10.7 mM, H = 1.01) in the absence of rephosphorylating substrates. These results are inconsistent with a phosphatase effect, because such an effect should be irreversible in cell-free, ATP-free patches. Instead, the results suggest that 2,3-Butanedione monoxime can inhibit KV2.1 channels directly from inside or outside of the membrane.