Preparations from livers of fed and fasted genetically diabetic and nondiabetic mice (C57BL/KsJ db/db, db/+, or +/+) were used to determine whether changes in pantothenate kinase activity and/or properties corresponded to hormonally directed changes in liver total CoA content. Livers of fasted, nondiabetic mice had ratios of pantothenate kinase (PAK) to lactate dehydrogenase (LDH) activity 1.6 times values for fed nondiabetic controls, and they had a total CoA content per milligram of DNA that was 1.8 times control values. Livers of fed genetically diabetic mice had values for PAK/LDH and total CoA per milligram of DNA that were 1.5 and 2.8 times, respectively, those of nondiabetic controls. Liver PAK from genetically diabetic mice was inhibited by acetyl-CoA to the same extent as enzyme from nondiabetic mice and by CoASH to nearly the same extent. Rat hepatocytes in primary culture incubated with dibutyryl cAMP + theophylline + dexamethasone had PAK/LDH levels 1.5 times those of cells not treated with hormonal effectors, and PAK was inhibited to the same extent by acetyl-CoA and nearly the same extent by CoASH. The data show an increase in extractable hepatic PAK activity under conditions in which the total CoA content is elevated, and they suggest that glucocorticoids and cAMP levels contribute to the increased PAK activity.