Impact of waterborne and trophic mercury exposures on cardiac function of two ecologically distinct Neotropical freshwater fish Brycon amazonicus and Hoplias malabaricus

Publication date: Available online 20 September 2017 Source:Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology Author(s): Diana A. Monteiro, Edwin W. Taylor, Francisco T. Rantin, Ana L. Kalinin Metal pollutants have been considered one of the main factors underlying the depletion of biodiversity in natural populations unbalancing aquatic environments. The aim of this study was to evaluate the effects of exposure to inorganic Hg on myocardial contractility and the electrocardiogram (ECG) of two ecologically distinct Neotropical fish species, namely: matrinxã (Brycon amazonicus) and trahira (Hoplias malabaricus). Matrinxãs were exposed to a sublethal concentration of 0.1mg L−1 of Hg in water for 96h. Trahiras were exposed to dietary Hg doses (0.45mg of Hg, each 4days, for 30days) using juvenile B. amazonicus as the prey vehicle. Hg exposures decreased myocardial isometric twitch force development, harmed contraction/relaxation dynamics and cardiac pumping capacity (CPC), and reduced the relative contribution of the calcium stored in the sarcoplasmic reticulum (SR) to excitation contraction (E-C) coupling in both fish species. Analysis of the ECG revealed that Hg impaired electrical conduction across the heart, inducing first degree atrioventricular block and lengthening the plateau phase of action potential duration. In trahira trophic doses of Hg induced a marked bradycardia, increasing the duration of the ventricular action potential a...
Source: Comparative Biochemistry and Physiology Part C: Toxicology and Pharmacology - Category: Toxicology Source Type: research