An investigation of some factors affecting levels of erythrocyte inorganic pyrophosphatase activity.

A reproducible method has been devised for assaying erythrocyte inorganic pyrophosphatase. The activity level in healthy individuals appears to be a constant characteristic. Population surveys have been carried out in 100 Europeans and 34 Indians. In each population an otherwise normal individual was found with activity approximately three standard deviations from the mean. Investigation of the family of one such individual indicated that this was an inherited characteristic. A few individuals with clinical abnormalities were examined and some were found to have activity levels above the normal range. High activity levels appeared to be associated with those diseases in which raised circulating reticulocyte levels are found. The rate of in vivo decay of erythrocyte inorganice pyrophosphatase has been measured in healthy individuals. The decay pattern appears to be of the constant logarithmic type. An estimate has been made of the activity in circulating reticulocytes, and the half life of the enzymes has been calculated.