An investigation into the effects of copper on the heart of rainbow trout (Onchorynchus mykiss) using an isolated heart perfusion preparation

There is a distinct lack o f literature available on the toxicity of heavy metals on the hearts of fish. Rainbow trout (Onchorynchus mykiss) were used in an in vitro study using Langendorff perfusion apparatus to investigate the toxicity of copper on the fish heart and the suitability of the technique with regard to the three Rs. Method development was carried out to determine the best in vitro conditions suited to the substance being tested. Hearts were perfused with a standard saline for 30 minutes and then exposed to 100(jmol f' (EN(IOO), 50|.imol 1"' (EN(50)) for 60 minutes, with no recovery period while one SOf^mol 1"' (ER(50) treatment was subjected to a 30 minute recovery period after exposure. Physiological viability parameters (heart rate, flow, cardiac output, stroke volume) were measured to determine general physiological effect of Cu^ ^on the viability of the heart. Biochemical measurements were also taken ( L DH in perfusates, tissue L D H , GSH, K"^, Na*, Ca^*, Mg'^* and Cu^* concentration) to examine more specific effects on mechanisms which may affect heart fimction, such as membrane stability, oxidative stress and ion transport. Copper-exposed hearts showed significant effects (ANOVA, P<0.05) on mean heart rate, cardiac output and stroke volume compared to control. Exposed hearts also showed increased release of L DH into the perfiisate compared to the control. ER(50) showed significantly lower (ANOVA, P <0.05) tissue L D H than control. A l l exposure groups showed depleted GSH reserves compared to control (ANOVA, P <0.05). Exposure groups also showed significant differences in tissue K"^, Na"^, Mg^* and Cu^'^concentrations compared to control (ANOVA, P