Optimum concentration of magnesium (Mg2+) to anesthetize octopus Octopus vulgaris
2009
Anraku, K., Kagoshima Univ. (Japan). Faculty of Fisheries | Goubayashi, H. | Nakamura, S. | Monteclaro, H.M. | Kasedou, T. | Onoue, T.
Optimum magnesium (Mgsup(2+)) concentration to anesthetize octopus Octopus vulgaris was determined behaviorally. In acute exposure experiments, eight octopuses were individually exposed to Mgsup(2+) at a series of concentration that ranged from 20 to 100 mM. Exposure to Mgsup(2+) suppressed octopus motions. At 40 mM, arm muscles relaxed in all tested individuals (8/8) and body color faded in 5/8 individuals. Respiration activities were reduced following the increase in Mgsup(2+) concentration and were stopped at 80 mM in 2/8 and at 100 mM in 4/8 individuals. In chronic exposure experiments, respiration rate and survival rate of five octopuses were studied during and after exposed to 30 mM Mgsup(2+) for 24 h. Respiration activity was reduced after 2 h exposure while muscle motions remained constant throughout the 24 h. All tested individuals survived magnesium exposure and recovered from anesthesia after they were returned in fresh seawater. We conclude that the optimum magnesium concentration to anesthetize O. vulgaris while keeping constant its respiration activity is 30 mM.
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