title: Effect of Different Formulations of Magnesium Chloride Used As Anesthetic Agents on the Performance of the Isolated Heart ofOctopus vulgaris.
abstract: Magnesium chloride (MgCl2) is commonly used as a general anesthetic in cephalopods, but its physiological effects including those at cardiac level are not well-characterized. We used anin vitroisolated perfused systemic heart preparation from the common octopus,Octopus vulgaris, to investigate: (a) ifin vivoexposure to MgCl2formulations had an effect on cardiac functionin vitroand, if so, could this impact recovery and (b) direct effects of MgCl2formulations on cardiac function.In vitrohearts removed from animals exposedin vivoto 3.5% MgCl2in sea water (20 min) or to a mixture of MgCl2+ ethanol (1.12/1%; 20 min) showed cardiac function (heart rate, stroke volume, cardiac output) comparable to hearts removed from animals killed under hypothermia. However, 3.5% MgCl2(1:1, sea water: distilled water, 20 min) produced a significant impairment of the Frank-Starling response as did 45 min exposure to the MgCl2+ ethanol mixture. Perfusion of the isolated heart with MgCl2± ethanol formulations produced a concentration-related bradycardia (and arrest), a decreased stroke volume and cardiac output indicating a direct effect on the heart. The cardiac effects of MgCl2are discussed in relation to the involvement of magnesium, sodium, chloride, and calcium ions, exposure time and osmolality of the formulations and the implications for the use of various formulations of MgCl2as anesthetics in octopus. Overall, provided that thein vivoexposure to 3.5% MgCl2in sea water or to a mixture of MgCl2+ ethanol is limited to ~20 min, residual effects on cardiac function are unlikely to impact post-anesthetic recovery.
authors.affiliation: Department of Biology, Ecology, and Earth Sciences, University of CalabriaArcavacata di Rende, Italy; Association for Cephalopod Research 'CephRes'Naples, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Pugliese
authors.affiliation: Department of Biology, Ecology, and Earth Sciences, University of Calabria Arcavacata di Rende, Italy.
authors.forename: Rosa
authors.initials: R
authors.lastname: Mazza
authors.affiliation: Association for Cephalopod Research 'CephRes'Naples, Italy; Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton DohrnNaples, Italy.
authors.forename: Paul L R
authors.initials: PL
authors.lastname: Andrews
authors.affiliation: Department of Biology, Ecology, and Earth Sciences, University of Calabria Arcavacata di Rende, Italy.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Cerra
authors.affiliation: Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn Naples, Italy.
authors.forename: Graziano
authors.initials: G
authors.lastname: Fiorito
authors.affiliation: Department of Biology, Ecology, and Earth Sciences, University of Calabria Arcavacata di Rende, Italy.
authors.forename: Alfonsina
authors.initials: A
authors.lastname: Gattuso
keywords: Anesthesia; Cephalopods; Directive 2010/63/EU; Octopus vulgaris; ethanol; magnesium chloride; systemic heart