Effects of FeSO4 on electrical and mechanical activity of guinea pig papillary muscles

FeSO4 0.1-0.7 mmol/L shortened the action potential duration, decreased the action potential amplitude (APA) and maximal upstroke velocity of 0 phase (Vmax), and reduced the contractile force of myocardium in a concentration-dependent manner. FeSO4 0.2 mmol/L depressed the APA and Vmax of papillary muscles in Tyrode's solution containing MnCl2 3 mmol/L, and reduced the APA, Vmax and duration of slow action potentials in potassium-depolarized papillary muscles. These results suggest that Fe2+ may inhibit the transmembrane movement of Ca2+ and Na+ in myocardial cells. This may be one of the mechanisms of heart failure and circulatory collapse in acute iron poisoning.