Determination of Plasma Phosphatase.

Abstract

The significance of phosphatase in bone physiology was suggested by Robison and his coworkers. Increased plasma phosphatase was recently reported by Kay in ostitis fibrosa, ostitis deformans, active rickets and osteomalacia. Kay also reported a method for the determination of plasma phosphatase. 1 In an experimental study of plasma phosphatase in ostitis fibrosa, which we produced in young guinea pigs and dogs by prolonged treatment with parathormone 2 , 3 , 4 , 5 we found Kay's method of determination of plasma phosphatase unsatisfactory. We have avoided the disadvantages of Kay's method by the use of an M/10 solution of sodium diethyl-barbiturate (veronal) as a buffer.∗ When it is added to plasma in the proportions which we employ, the resulting mixture has a pH of about 8.6. This reaction is not changed after the addition of the substrate—a solution of sodium beta-glycerophosphate (Boots Drug Company, Nottingham, England) containing about 5 mg. of phosphorus per cc.† ‡ Nor does the pH change perceptibly during the action of the phosphatase, even when continued for 72 hours.