BDS-I

BDS-I is a 43 amino acid peptidyl toxin isolated from the sea anemone Anemonia sulcata venom. It is reported to be a selective blocker of K_V3.4 K⁺ channel. BDS-I blocks 60% of the K_V3.4 current in COS-transfected cells at a concentration of 2.5 µM. The blocking effect is rapid, direct and reversible¹. Recently it was shown that it blocks other K_V3 channels with similar potencies².

BDS-I inhibits K_V currents in carotid body cells³, an effect which disappears after chronic hypoxia, establishing the unique role played by K_V3 channels in the response to hypoxia⁴. BDS-I (2.5 µM) also reduces the native transient K⁺ current and increases the action potential duration in hippocampal granule neurons⁵. In corneal epithelial cells BDS-I (400 nM) inhibits most of the detected K_V current⁶. In magnocellular neurosecretory neurons of the hypothalamus, 100 nM BDS-I inhibits about half of the K_V current and increases the action potential duration⁷. In fast spiking neurons from different brain areas, 2 µM BDS-I inhibits part of the K_V current and broadened the action potential and reduces spike frequency⁸.

BDS-I also produces broadening of the spike and accelerates the upstroke of the action potential by modulating voltage-gated Na⁺ channels. It enhances TTX-sensitive Na⁺ channels (highly effective on Na_V1.7 channels), and weakly inhibits TTX-resistant Na_V channels⁹.