Cytosolic calcium in the myocardium is rapidly accumulated during ischemia and has been correlated with the attenuation of functional recovery in the myocardium. The aged myocardium is more sensitive to ischemia and accumulates significantly more cytosolic calcium than either the newborn or the mature myocardium. Modification of the age-related propensity to increased cytosolic calcium accumulation may be achieved through the use of magnesium or potassium/magnesium cardioplegia. Improved postischemic ventricular function obtained with magnesium or potassium/magnesium cardioplegia may have important implications in the reduction of myocardial morbidity and mortality.