Bioassay of Vitamin K by Intracardial Injection in Deficient Adult Male Rats

Abstract
The biological activity of vitamin K was determined by intracardial injection in partially depleted adult male rats. Prothrombin levels rose rapidly after the injection of phylloquinone. Response to menadione was delayed for several hours. The relative molar activity of several forms of vitamin K was determined. Menaquinones with side chains containing more than six isoprene units were up to 25 times as active as phylloquinone.