The effects of the heavy metals cadmium and zinc on the contraction of ventricular fibres in fish

1. The force-frequency relationship has been determined in strips of ventricular fibres of sea bass and dogfish after treatment with several concentrations of cadmium and zinc. 2. At increasing metal concentrations a reduction of twitch force is observed in the heart fibres, the reduction being similar in the two species for each metal. 3. Cadmium shows a more powerful effect since comparable reduction is obtained at 10 times lower concentration. 4. The removal of metal concentrations in previously-treated strips does not allow the initial force to recover. 5. The results are discussed in relation to the consequences of metal exposure on the heart function and the repercussion on fish performance. © 1991.