The deceleration of the heart frequency in the waterfleaDaphnia magna by adrenoceptor agonists and antagonists

Abstract

Beat-to-beat measurements with 30 micro-seconds accuracy were carried out in order to determine the chronotropic effects on the heart of Daphnia magna induced by adrenoceptor agonists and antagonists dissolved in water. Agonists and antagonists were either ineffective or lowered the heart frequency (P < 0.05). In addition, the negative chronotropic effect of the agonist epinephrine could not be blocked by the antagonist propranolol. It may, therefore, well be that the drug actions were not mediated through adrenoceptors.

Prediction and experimental validation of acute toxicity of β‐blockers in Ceriodaphnia dubia

“…Propranolol reduces the heart rate at concentrations greater than 0.3 mg/L. No effect was detected at less than 26.5 mg/L for MET [21,23]. This effect does not seem to be mediated through specific adrenoceptors but, rather, through disruption of nervous messages implied in the control of heart rate, probably by reducing the transmission speed [23,24].…”

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“…Daphnia magna, unlike most arthropods, has a myogenic heart responding to a variety of agonists and antagonists, in a similar way to that in vertebrates, therefore it has been used by some authors as a model organ for determination of effects induced by bioactive agents (Stein et al, 1966;Postmes et al, 1989;Villegas-Navarro et al, 2003;Campbell et al, 2004;Okushima et al, 2014). The present study showed a negative chronotropic effect in Daphnia magna induced by CO alone at both concentrations, however more increased bradycardia was noted at the higher concentration of CO.…”

Multi-generational effects of propranolol on Daphnia magna at different environmental concentrations

“…Norepinephrine and epinephrine, the catecholamine ligand to the b-adrenergic receptor, were quantified in D. magna (Ehrenstr€ om and Berglind, 1988), but adrenergic receptors are not yet characterized. Exposure of D. magna to catecholamines has shown inconsistent and opposite effects in a range of concentrations from 10 -6 M to 10 -4 M (Postmes et al, 1989;Krijgsman and Krijgsman-Berger, 1951). The observed response is quite different from vertebrates because the neurotransmitter has the function of accelerating heart rates, so other candidates for molecular targets besides b-adrenergic receptors need to be considered.…”

“…Researches employing sub-lethal endpoints of fish related to reproduction, behavior, development, cardiac activity, and detoxification reported adverse effects with a trace amount of propranolol in a range from several hundreds to thousands ng/L (Finn et al, 2012;Huggett et al, 2002;Lorenzi et al, 2012). In the case of invertebrates, the species have been relatively less focused on due to their lower sensitivity and contrary assumption to pharmaceutical effects due to a lack of information on the molecular target (Ericson et al, 2010;Stanley et al, 2006;Dzialowski et al, 2006;Postmes et al, 1989). However, harmful effects on invertebrates have rarely been reported, and their sublethal endpoints are similar to those of fish (De Lange et al, 2006;Fong and Ford, 2014;Borgmann et al, 2007).…”

“…Therefore, whether effect of propranolol on aquatic organism was underestimated or not should be confirmed. We used D. magna, one of the keystone species in the aquatic ecosystem, as a test organism because the species offers the advantages of a short life span and asexual reproduction for a multi-generational exposure study (Mehvar et al, 2001;Nickerson et al, 2003;Stanley et al, 2006;Postmes et al, 1989). This study is part of a project that aims to understand adverse outcomes and to predict multi-generational effects of human pharmaceutical ingredients on aquatic organisms.…”