IN-VITRO ZINC STIMULATION OF ANGIOTENSIN-CONVERTING ENZYME-ACTIVITIESIN HUMAN PLASMA

We evaluated plasma angiotensin-converting enzyme (ACE) activity and i n vitro zinc stimulation of ACE as a method to assess zinc nutriture i n two groups of humans. humans. These included a total of 135 indigent African-American women who participated in a double-blind trial to ev aluate the effect of oral zinc supplementation (25 mg/day as zinc sulf ate) on pregnancy outcome and 15 healthy young males who volunteered i n a study to evaluate the effect of low-zinc intake (0.5 mg of zinc pe r day for 12 days) on the concentration of erythrocyte metallothionein under controlled metabolic conditions. In the first group, increased birth weight and head circumference of newborns newborns by material z inc supplementation led to the conclusion that inadequate maternal zin c nutriture existed. However, there were no differences in the activit ies of plasma ACE and ACE stimulation by the in vitro addition of zinc between the zinc-supplemented and placebo groups. Both of these these values remained unchanged during pregnancy. In the second group, plas ma ACE activity remained unchanged after a low-zinc diet for 12 days a lthough erythrocyte metallothionein and zinc concentrations declined. We conclude that these tests are insensitive indicators of zinc nutrit ure in humans.