Protein synthesis in cell-free systems from totally ischemic rat myocardium

Ribosomes and cell sap were isolated at different times from excised rat hearts stored in a moist chamber at 37 degrees C and their capacity for protein synthesis was tested. The incorporation rate of labeled amino acids by ribosomes with cell sap from control hearts showed a slow decrease after the first hour of incubation. Polysome profiles as well as incorporation of [14C]phenylalanine in the presence of polyuridylic acid indicated an increase in the amount of monoribosomes during storage of the organ. The activity of cell sap prepared from such hearts after 1 hr and measured with ribosomes from control hearts was also decreased. The reduction in the capacity for protein synthesis noted separately with ribosomes and with cell sap from stored hearts is additive if both components are prepared from stored hearts.