Small concentrations of mercury enhances positive inotropic effects in the rat ventricular myocardium

Small concentrations of mercury reduce the force development of the rat right myocardium and inhibit the sodium pump. This inhibition might increase the amount of activator Ca2+ in the sarcoplasmic reticulum available upon activation. We further investigated whether this action could potentiate positive inotropic effects produced by Ca2+ increment (0.62-1.25 mM) and isoproterenol (20 nM). Right ventricular strips contracting isometrically were treated with 0.1 and 1 μM HgCl2. Results showed that after HgCl2 treatment the magnitude of both inotropic interventions was increased. Considering that Hg2+ amongst its effects induces hypertension and might be associated with cardiovascular diseases these potentiating effects might have hazardous consequences.