Activity of Hepatic Phosphoenolpyruvate Carboxykinase and Pyruvate Carboxylase in Malnourished California Sea Lions (Zalophus californianus)
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Under conditions of starvation or caloric restriction, gluconeogenesis produces the majority of glucose within mammalian cells. While starvation has been shown to stimulate gluconeogenesis in a variety of species, many California sea lions (CSLs) (Zalaphus californianus) that are treated for malnutrition at The Marine Mammal Center in Sausalito, California die during rehabilitation from presumed hypoglycemic shock. In this study, a procedure previously used to assay hepatic enzymes in mice was successfully adapted to measure the activity of phosphoenolpyruvate carboxykinase (PEPCK) and pyruvate carboxylase (PC) in CSLs. Assays performed on liver samples harvested at various intervals post-mortem indicated that both PC and PEPCK enzymes are relatively stable within the 24 hour period after death. Further assays indicated that there does not appear to be a significant difference between PEPCK and PC activity in malnourished CSLs and PEPCK and PC activity in control CSLs. The results of this study suggest that hypoglycemic shock in malnourished CSLs is not due to diminished gluconeogenic activity.