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

Author(s)

Monteiro, Diana A. ^[1] ; Taylor, Edwin W. ^[2] ; Rantin, Francisco T. ^[1] ; Kalinin, Ana L. ^[1]

Affiliation

^[1] Fed Univ Sao Carlos UFSCar, Dept Physiol Sci, BR-13565905 Sao Carlos, SP - Brazil

^[2] Univ Birmingham, Sch Biol Sci, Birmingham B15 2TT, W Midlands - England

• Document type: Journal article
• Source: COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY C-TOXICOLOGY & PHARMACOLOGY; v. 201, p. 26-34, OCT 2017.
• Web of Science Citations: 3

Abstract

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: matrinxa (Brycon amazonicus) and trahira (Hoplias malabaricus). Matrinxas were exposed to a sublethal concentration of 0.1 mg L-1 of Hg in water for 96 h. Trahiras were exposed to dietary Hg doses (0.45 mg of Hg, each 4 days, for 30 days) 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 and delaying atrial and ventricular depolarization. These findings indicate that both acute and long-term Hg exposure, by different routes is cardiotoxic to matrinx5 and trahira. Hg potently impaired intracellular calcium kinetics in the cardiomyocytes, myocardium contractility, and electrical conduction across the heart, all of which can be implicated in decreased cardiac output and putative heart failure. (AU)

• FAPESP's process: 06/50772-6 - Effect of inorganic mercury on the cardiac function and on oxidative stress biomarkers in matrinxã, Brycon amazonicus (Spix & Agassiz, 1829) and in traíra, Hoplias malabaricus (Bloch, 1794)
• Grantee: Diana Amaral Monteiro
• Support Opportunities: Scholarships in Brazil - Doctorate