Distribution of Zinc and Copper in Maternal and Cord Blood at Delivery

Abstract

For 17 normal births, the concentrations of trace metals (zinc and copper) and related metalloenzymes, i.e., carbonic anhydrase isoenzymes (CA-I and CA-II) and Cu₂Zn₂superoxide dismutase (SOD₁) were simultaneously determined in maternal and cord blood at delivery. Eleven healthy nonpregnant women served as controls. CA-I concentration in maternal erythrocytes was higher than in controls (p < 0.05), whereas the concentrations of both CA isoenzymes in cord erythrocytes were in the range of one seventh to one ninth of those in controls. On the other hand, the erythrocyte SOD₁ concentration was constant. A very low total zinc concentration was noted in cord erythrocytes, and this was due to the low concentrations of both CA isoenzymes. Total copper concentration in maternal erythrocytes was significantly lower than in controls (p < 0.05); in contrast, that in cord erythrocytes was significantly higher than in controls (p < 0.05). Thus, variations in erythrocyte copper concentrations are due to changes in other forms of copper (not SOD₁-derived). Copper concentration in maternal plasma was about three times higher than in controls, while copper concentration in cord plasma was less half of that in control plasma. Conversely, zinc concentration in cord plasma was significantly higher than in controls (p < 0.05). The concentrations of these metals in maternal erythrocytes and plasma were significantly different from the respective concentrations in cord erythrocytes and plasma. Likewise, the concentrations of these metals in maternal and cord erythrocytes contrasted with the corresponding concentrations in their plasma.

Maternal Blood Distribution of Zinc and Copper during Labor and after Delivery

“…Since SOD | concentration in the NST was higher than in controls, the NST total copper con centration in erythrocytes appeared to be higher as compared to the control value. In contrast, it has been demonstrated that total copper concentration in maternal erythro cytes immediately after delivery (which cor responds to phase 4 in our study) is signifi cantly lower than in nonpregnant women although the SOD] concentration does not vary substantially [6,18], In the present study, however, no difference was noted be tween them. This disparity remains to be elucidated since the results on plasma copper concentration are in good agreement with those of previous studies [2,6,18], Total plasma zinc concentration did not decrease significantly in the NST, there being a nearly 10% decline below the control values.…”

“…In contrast, it has been demonstrated that total copper concentration in maternal erythro cytes immediately after delivery (which cor responds to phase 4 in our study) is signifi cantly lower than in nonpregnant women although the SOD] concentration does not vary substantially [6,18], In the present study, however, no difference was noted be tween them. This disparity remains to be elucidated since the results on plasma copper concentration are in good agreement with those of previous studies [2,6,18], Total plasma zinc concentration did not decrease significantly in the NST, there being a nearly 10% decline below the control values. This result was inconsistent with those of many studies in which the mean zinc concentra tion in maternal plasma/serum is apparently lower than in normal nonpregnant individu als [1][2][3][4], The discrepancy is probably due to the fact that there was a rising tendency in aj-MG-bound zinc concentration in the NST.…”

“…To our knowledge, however, zinc metabolism in maternal blood during the different stages of parturition has not been completely defined. We have pre viously reported the distributions of zinc and copper in maternal and cord blood at delivery [6]. In the present study we have determined the effects of vaginal delivery on zinc and copper fractions in maternal eryth rocytes and plasma and furthermore at tempted to correct these plasma values for changes in plasma volume.…”

Maternal, Placental and Cord Zinc Components in Healthy Women with Different Levels of Serum Zinc

“…Cord zinc erythrocyte concentrations were about one fourth the maternal values, as previously observed [11,27], probably due to lower concentrations of carbonic anhydrase isoenzymes in cord compared to maternal erythrocytes [11], In contrast, metallothionein concentrations were similar in maternal and cord erythrocytes in all groups but only in cord, erythrocyte metallothionein and zinc levels tended to be correlated, suggesting some difference in maternal and cord regula tion of erythrocyte metallothionein. Pregnant women at delivery were shown to have slight 90 Biol Neonate 1997:72:84-93…”

“…Most studies on maternal-fetal transfer of zinc have related maternal and cord serum zinc, observing either a significant correlation [6,7] or no correlation [8][9][10], A few studies have measured maternal serum zinc in rela tion to other maternal indices of zinc status [11][12][13] and/or to placental zinc [12,14] and cord serum components [4] in normal preg nancies, but the physiological significance of variations in serum zinc in healthy pregnant women is still unclear.…”