Effect of Different Formulations of Magnesium Chloride Used As Anesthetic Agents on the Performance of the Isolated Heart of Octopus vulgaris.

Chiara Pugliese,Paul L R Andrews,Maria C Cerra,Alfonsina Gattuso,Rosa Mazza,Graziano Fiorito

doi:10.3389/fphys.2016.00610

Chiara Pugliese, Paul L R Andrews + Show 4 more

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https://doi.org/10.3389/fphys.2016.00610

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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 an in vitro isolated perfused systemic heart preparation from the common octopus, Octopus vulgaris, to investigate: (a) if in vivo exposure to MgCl2 formulations had an effect on cardiac function in vitro and, if so, could this impact recovery and (b) direct effects of MgCl2 formulations on cardiac function. In vitro hearts removed from animals exposed in vivo to 3.5% MgCl2 in 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 MgCl2 are 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 MgCl2 as anesthetics in octopus. Overall, provided that the in vivo exposure to 3.5% MgCl2 in 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.

Highlights

Cephalopods are very active creatures (O’Dor et al, 1990; Hanlon and Messenger, 1996; Boyle and Rodhouse, 2005), and have been utilized for more than a century as experimental animals in a broad spectrum of studies in biological sciences
Our results suggest that MgCl2 formulations have some direct effects on the heart, in vivo they are suitable for inducing anesthesia, provided exposure time is carefully controlled
The results provide insights into the physiological effects on the systemic heart of magnesium chloride formulations used for anesthesia of O. vulgaris

Summary

Introduction

Cephalopods are very active creatures (O’Dor et al, 1990; Hanlon and Messenger, 1996; Boyle and Rodhouse, 2005), and have been utilized for more than a century as experimental animals in a broad spectrum of studies in biological sciences (for review see for example: Young, 1985; Hochner et al, 2006; Borrelli and Fiorito, 2008; Hochner, 2012; Huffard, 2013; Ponte et al, 2013; Fiorito et al, 2014). Cardiac Effects of Magnesium Chloride in Octopus (e.g.,: Lo Bianco, 1909; Grimpe, 1928; Young, 1971a). A description of these attempts is already available in Grimpe (1928), and a summary of events occurring during anesthesia with octopus, for example, are found in the classic contribution by Young (1971a). General anesthesia is necessary to perform surgical or investigative procedures including those required for veterinary and research purposes. In contrast for cephalopods, whilst the potential anesthetic properties of about 20 agents have been explored (for review see for example: Gleadall, 2013; Fiorito et al, 2015), few studies regarding the physiological effects on the animals, including the cardiac ones, are available (review in: Andrews et al, 2013)

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