Experimental method for recording epicardium potentials and cardiac myocyte shortening

The hemodynamic changes observed in advanced stages of heart diseases are often accompanied by changes in the electrical and mechanical properties of cardiac myocytes. The objective of this work is to develop an experimental method for recording ventricle epicardium potentials in isolated rat hearts and isolated cardiac myocyte shortening. Briefly, rat heart was removed, aorta was cannulated and coronary arteries were retrogradely perfused with heated and oxygenated buffer solutions. Ag-AgCl electrodes fixed in a silicone pouch placed around the heart were used to measure epicardium potentials. The perfusion was switched to an enzyme-containing solution for digestion of the heart and obtaining isolated cardiac myocytes. Measurements of shortening were made in cells electrically stimulated. The results suggest the possibility of relating the electrical behavior of the whole heart with mechanical properties of cardiac myocytes and may represent an useful tool in basic cardiac research.