High energy phosphate levels in hearts arrested and stored in SOMAH. Cardiac tissue biopsies from left ventricle were obtained for determination of HEP including ATP and CP levels in 4 and 21°C SOMAH cardioplegia group hearts pre and post 5-hour storage. There was a temperature of cardioplegia arrest dependent increase in HEP concentrations in the hearts. A: Control; B: 5 hour storage; C: Normalized values (5 hours with respect to 0 hour). Each bar represents mean ± SEM of n = 5 for each group. * Significantly different from 4°C cardioplegia group hearts.