Effects of vitamin K-deficient diets and fasting on blood coagulation factors in conventional and germ-free rats.

Feeding of vitamin K-deficient diets or fasting produced vitamin K deficient syndromes in both conventional and germ-free male rats in 3 days, increasing prothrombin time (PT), activated partial thromboplastin time (APTT), plasma and liver descarboxyprothrombin (PIVKA) levels and liver gamma-glutamylcarboxylase activities, but decreasing plasma clotting factor VII and prothrombin levels. These changes were not found when daily 30 micrograms/rat of vitamin K1 was injected during this period. The changes caused by fasting were comparable with those caused by a diet containing 20-30 ng/g of vitamin K1, while a diet containing less than 5 ng/g caused greater changes in both conventional and germ-free rats. Germ-free rats on a diet containing sufficient amounts of vitamin K1 showed PT and APTT values similar to those in conventional rats, but lower plasma clotting factor levels and higher PIVKA and microsomal gamma-glutamylcarboxylase activities. The values for PT, APTT, factor VII, prothrombin and PIVKA in the fasted germ-free rats were almost the same as those in the fasted conventional rats. These findings suggest that menaquinones synthesized in the large intestine are not utilized sufficiently to prevent vitamin K deficiency in rats.