Effects of the organophosphorus pesticide Folisuper 600 (methyl parathion) on the heart function of bullfrog tadpoles, Lithobates catesbeianus (Shaw, 1802)

Abstract

The aim of this work was to evaluate whether the heart function of bullfrog tadpoles (25 Gosner stage) is affected by their acute exposure (48 h) to a sub-lethal concentration (10 µg.L -1 ) of the active principle of the organophosphorus pesticide Folisuper 600R (methyl parathion -MP). Our results demonstrated that MP causes not only a reduction in tadpoles' cardiac ventricular mass, resulting in a marked reduction in their cardiac twitch force, but also impairs their swimming performance, irrespective of increasing their heart rate. Together, these findings indicate that low and realistic concentration of MP have a negative impact on tadpoles' performance, jeopardizing their survival. Keywords: methyl parathion, cardiac performance, bullfrog tadpoles, Lithobates catesbeianus (Rana catesbeiana).Efeitos do pesticida organofosforado Folisuper 600 (metil paration) sobre a função cardíaca de girinos de rã-touro, Lithobates catesbeianus (Shaw, 1802) ResumoO objetivo do presente estudo foi avaliar se a função cardíaca de girinos de rãs-touro (estágio 25 de Gosner) é afetada pela exposição aguda (48h) a uma concentração sub-letal (10 µg.L -1 ) do princípio ativo do pesticida organofosforado Folisuper 600R (metil paration -MP). Nossos resultados demonstraram que o MP ocasionou não apenas uma redução na massa ventricular cardíaca dos girinos, como também provocou uma redução na sua força de contração cardíaca e de seu desempenho natatório, a despeito de ter sido observado um aumento de sua freqüência cardíaca. Conjuntamente, os achados aqui obtidos indicam que uma baixa e realística concentração de MP exerce um impacto negativo sobre o desempenho dos girinos, ameaçando sua sobrevivência.Palavras-chave: metil paration, desempenho cardíaco, girinos de rã-touro, Lithobates catesbeianus (Rana Catesbeiana).

Cardiac biomarkers as sensitive tools to evaluate the impact of xenobiotics on amphibians: the effects of anionic surfactant linear alkylbenzene sulfonate (LAS)

“…Therefore, the reduction in the tadpoles' activity level in response to LAS exposure is probably due to the fact that this xenobiotic inhibits acetylcholinesterase's (AChE) activity in the motor end-plate of the skeletal muscle fiber, impairing tadpoles' swimming performance. Similar results have been observed in bullfrog tadpoles in response to the exposure to other lipophilic contaminants, such as methyl parathion (Costa et al, 2015) and endosulfan (Denoël et al, 2013). In addition, studies have demonstrated a decrease in the swimming activity in response to the inhibition of AChE in some fish species (Brewer et al, 2001;Rao et al, 2005;Ballesteros et al, 2009).…”

“…Results are presented as Means ± S.E. only been undertaken recently (Costa et al, 2008(Costa et al, , 2015Dal-Medico et al, 2014;Rissoli et al, 2016;Salla et al, 2016).…”

“…fragmentation of their habitats, increased ultraviolet radiation, global warming, emerging infectious diseases and the presence of contaminants, notably those in aquatic environments (Blaustein et al, 1994;Collins and Storfer, 2003;Roe et al, 2005;Collins, 2010;Hof et al, 2011;Abdalla et al, 2013;Van Meter et al, 2014;Costa et al, 2015Carvalho et al, 2017). Indeed, several studies have provided evidence that aquatic contaminants are among the main causes of amphibian declines (Collins, 2010;Blaustein et al, 2011).…”

Novel findings on the impact of chytridiomycosis on the cardiac function of anurans: sensitive vs. tolerant species

“…Among the effects of cholinergic overstimulation previously described in mammals are tearing, sweating, cardiorespiratory alterations, salivation, changes in the central nervous system, bradycardia, as well as muscle necrosis ( Nunes, Carvalho & Guilhermino, 2005 ). Costa et al (2015) also demonstrated this bradycardia in bullfrog tadpoles exposed to environmental stressors (i.e., exposure to an organophosphate).…”

“…This results in a negative chronotropic response, with reduction of the self-depolarization rate of pacemaker cells ( Pelster et al, 1993 ). Therefore, Bd could either stimulate the parasympathetic system, or inhibit the activity of the enzyme acetylcholinesterase (AChE), which is responsible for ACh hydrolysis ( Costa et al, 2015 ). Consequently, ACh accumulates in the synaptic cleft.…”