We propose to determine the sequence of appearance of the 4 specific gluconeogenic enzymes and of phosphoenolpyruvate carboxykinase ferroactivator in the fetal and post-natal development of a primate species to establish when infants of the species might be capable of self-sufficient gluconeogenesis. We will also prepare pure phosphoenolpyruvate carboxykinase (PEPCK) and its ferroactivator from normal (accident victims) human livers and from the livers of SIDS victims. These will be supplied by pathologists. The pure proteins will be characterized and used to prepare antibodies (in rabbits) to these two proteins. The antibodies will be used in a radio-immunoassay to measure the amounts of PEPCK and of ferroactivator proteins in normal and SIDS livers. These values will be compared with those obtained by assay of enzymic activity to determine the nature of the defect in the PEPCK activity in livers from SIDS victims. In infant rats, we will examine the influence of anoxic periods and of prolonged hypoxia on PEPCK activity. Conversely, we will block PEPCK in fasted infant rats with quinolinate or 3-mercaptopicolinate to determine whether the resulting hypoglycemia will induce apnea. The purpose of these experiments is to determine whether prevention of SIDS should be directed toward control of apnea or toward regulation of PEPCK and gluconeogenesis.