THE RELATIVE EFFECTS OF PHYLLOQUINONE AND MENAQUINONE-4 ON THE BLOOD-COAGULATION FACTOR SYNTHESIS IN VITAMIN K-DEFICIENT RATS

Rats were made vitamin K-deficient by feeding them a 1:1 (w/w) mixture of a commercial vitamin K-depleted diet and boiled white rice. After one week of treatment the rats had developed severe vitamin K deficien cy, resulting in Thrombotest(R) values of 5-10% of the initial values. In this experimental system the efficacy of phylloquinone (K1) was co mpared with that of menaquinone-4 (MK-4) by measuring the extent to wh ich the Thrombotest was normalized after the administration of varying doses of the respective vitamins. Oral administration of the vitamins showed that the efficacy of K1 was at least two-fold higher than that of MK-4. As comparable results were obtained after subcutaneous admin istration of the vitamins, we conclude that after oral administration the intestinal absorption had been quick and nearly complete. A less p ronounced effect of K1 and MK-4 was found after colorectal administrat ion. For both forms of vitamin K relatively high amounts (well above t he physiological concentration) were required before significant effec ts on the Thrombotest could be observed. Therefore these data demonstr ate the importance of sufficient dietary vitamin K consumption in rats . The efficacy of other menaquinones may be investigated in the same e xperimental animal model system.