Total, protein-bound, and ultrafilterable calcium in maternal and fetal plasmas

Delivoria‐Papadopoulos, Maria; Battaglia, F. C.; Bruns, Paul D.; Meschia, Giacomo

doi:10.1152/ajplegacy.1967.213.2.363

Cited by 82 publications

(29 citation statements)

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“…The ionized calcium is also increased 0.25-0.50 mM above the maternal value in fetal rodents (148,340,422), confirming that true hypercalcemia is present relative to maternal and normal adult values. Although only ϳ50% of serum calcium is ionized in the adult rodent, within fetal rodents ϳ80% of calcium is free or ionized (148,340). It is unknown how early in gestation the serum calcium becomes increased compared with the maternal value, but it has been demonstrated at all time points for which it has been technically possible to measure it.…”

Section: Animal Datamentioning

confidence: 64%

“…Typically the fetal serum calcium is 0.30 -0.50 mM or higher than the maternal level in rhesus monkeys (189,524), lambs (148,201,435,505), calves (201,715), rodents (201,338,340,342,346,347,623), pigs (98,101,353), and foals (201). The ionized calcium is also increased 0.25-0.50 mM above the maternal value in fetal rodents (148,340,422), confirming that true hypercalcemia is present relative to maternal and normal adult values. Although only ϳ50% of serum calcium is ionized in the adult rodent, within fetal rodents ϳ80% of calcium is free or ionized (148,340).…”

Section: Animal Datamentioning

confidence: 87%

“…Human fetuses share the finding of an elevated serum calcium and ionized calcium, typically 0.30 -0.50 mM above the maternal level (143,148,463,523,594,595). This has been demonstrated at 15-20 wk of gestation by fetoscopy (453), and at delivery of preterm singleton and twin pregnancies (mean gestational age 33 wk) (152).…”

Section: Human Datamentioning

confidence: 89%

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Bone Development and Mineral Homeostasis in the Fetus and Neonate: Roles of the Calciotropic and Phosphotropic Hormones

Kovacs

2014

Physiological Reviews

208

188

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Mineral and bone metabolism are regulated differently in utero compared with the adult. The fetal kidneys, intestines, and skeleton are not dominant sources of mineral supply for the fetus. Instead, the placenta meets the fetal need for mineral by actively transporting calcium, phosphorus, and magnesium from the maternal circulation. These minerals are maintained in the fetal circulation at higher concentrations than in the mother and normal adult, and such high levels appear necessary for the developing skeleton to accrete a normal amount of mineral by term. Parathyroid hormone (PTH) and calcitriol circulate at low concentrations in the fetal circulation. Fetal bone development and the regulation of serum minerals are critically dependent on PTH and PTH-related protein, but not vitamin D/calcitriol, fibroblast growth factor-23, calcitonin, or the sex steroids. After birth, the serum calcium falls and phosphorus rises before gradually reaching adult values over the subsequent 24 -48 h. The intestines are the main source of mineral for the neonate, while the kidneys reabsorb mineral, and bone turnover contributes mineral to the circulation. This switch in the regulation of mineral homeostasis is triggered by loss of the placenta and a postnatal fall in serum calcium, and is followed in sequence by a rise in PTH and then an increase in calcitriol. Intestinal calcium absorption is initially a passive process facilitated by lactose, but later becomes active and calcitriol-dependent. However, calcitriol's role can be bypassed by increasing the calcium content of the diet, or by parenteral administration of calcium.

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Section: Animal Datamentioning

confidence: 64%

Section: Animal Datamentioning

confidence: 87%

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Bone Development and Mineral Homeostasis in the Fetus and Neonate: Roles of the Calciotropic and Phosphotropic Hormones

Kovacs

2014

Physiological Reviews

208

188

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“…The apparent K, for CaCI, was 0.37 + 0.02 mM (mean + S.D.) in the presence of 5 mM ATP from four placental preparations under these conditions. The total ATPase activity also determined during the Ca" uptake experiments and was approximately 0.17 * 0.02 pmole/ mg/min in the microsomal fraction.…”

Section: Inhibitors a N D T H E Effects Of Other Ligandsmentioning

confidence: 77%

Calcium Uptake and Binding by Membrane Fractions of Human Placenta: ATP-dependent Calcium Accumulation

Whitsett

Tsang

1980

Pediatr Res

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SummaryAn ATP-dependent calcium (Ca2+) sequestration activity was demonstrated in membrane vesicles prepared from the human term placenta. Microsomal and brush border membrane fractions accumulated Ca2+ within a vesicular space by a saturable process requiring Mg2+ and ATP. The "uptake" activity was enriched sixfold in a microsomal membrane fraction and was only 1.5-fold enriched in purified brush border membranes compared to the activity present in the filtered homogenate. Mitochondria1 inhibitors such as azide and oligomycin did not inhibit Ca2+ uptake in --these preparations. The process was temperature dependent and dis~laved Michaelis-Menten-like kinetics with reswct to free Ca2+ . -concentrations. At 30°C, the V,, was 1.05 nmole/mg/min; K , = 74 nM for free Ca2+ in the microsomal fraction. Oxalate and phosphate enhanced uptake in both fractions. Ca2+ uptake activity was not associated with Ca2+-stimulated ATPase, alkaline phosphatase, or other brush border markers during cell fractionation. The characteristics of the Ca2+ uptake process contrasted sharply with those of Ca2+-stimulated ATPase, and a Ca2+-stimulated, Mg2+dependent ATPase activity could not be identified in these membrane vesicle preparations.

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“…Hypercalcemia of much longer duration occurs physiologically in the human fetus over the final weeks of gestation, during which time an active placental transport mechanism keeps circulating calcium concentrations in the fetus about 2 mg/dl above corresponding maternal plasma levels (35,36). Mean calcium concentrations in human cord blood have varied from 9.2-1 1.0 mg/dl in several reports (2,14,36). The mean value of 10.6 mg/dl in this study is above the 2 SD range of serum calcium established in our laboratory for normal adults (9.4 + 0.85 mg/dl, n = 118).…”

Section: Discussionmentioning

confidence: 99%

Parathormone and Perinatal Calcium Homeostasis

et al. 1979

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Summawand Rudd (49) have observed mean PTH concentrations in cord Plasma measured the first parathormone (PTH) and calcium concentrations were in 309 specimens collected from 190 newborns during 7 days of life. The patient material consisted of 51 preterm, 130 term, and 9 postterm infants, including 22 infants of diabetic mothers (IDM), 38 infants with hypocalcemia, and 25 asphyxiated infants. PTH was detectable, although in low concentrations, in cord blood samples despite the presence of elevated calcium concentrations. Postpartum, PTH concentrations in term, appropriate for gestational age (AGA) infants remained low during the first 2 days of life; a significant ( P < 0.05) and sustained increase in plasma hormone levels was noted starting on day 3. PTH concentrations in IDM and preterm infants remained low for 3 days and a significant hormone increase did not occur until day 4.Hypocalcemia was common in IDM and asphyxiated infants; these infants accounted for two-thirds of all hypocalcemic infants. The profde of plasma calcium in IDM during the fust week of life was different than that of any other group of infants. Plasma calcium concentrations remained depressed over this period of time and exhibited a temporary drop on day 4 accompanied by an increase in plasma PTH levels. Asphyxiated infants exhibited low plasma calcium concentrations, despite PTH levels that were significantly ( P < 0.007) higher than those of age-matched term AGA newborns. SpeculationBasal PTH secretion is present at birth, several days before the parathyroid glands appearto become responsive to hypocalcemia. Furthermore, in cord blood PTH is detectable in spite of elevated calcium concentrations. The present observatiois suggest that nonsuppressible PTH secretion, previously described in short-term animal ex~eriments. also occurs in the human fetus ex~osed to long-standing intrauterine hypercalcemia, with the implication that PTH secretion in man may be regulated by control mechanisms in addition to calcium feedback. There is anatomical and pharmacologic evidence to implicate the autonomic nervous system in this control.Hypocalcemia is a frequent problem in early postnatal Life (1 1, 20, 37, 47). Between 1970 and 1971,44 of 1390 newborns (3.2%) delivered at Harbor General Hospital, UCLA, presented with socalled "first day hypocalcemia" defmed as serum calcium levels of 5 7 mg/dl during the first 36-48 hr of life (32). Two-thirds of these infants were premature (gestation less than 38 weeks). The etiology of first day hypocalcemia remains unclear. A number of authors (17,19,46) (1 17 k 17), but were unable to detect any correlation between serum-ionized calcium on the one hand and PTH levels on the other in either maternal, cord, or infant blood between birth and age 7 days. David and Anast (13) reported similar results, yet they did observe an increase in plasma PTH in 23 of 36 infants beyond age 48 hr, and this increase correlated with a gradual rise of the low neonatal calcium concentrations toward normal. Finally, there are conflic...

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Total, protein-bound, and ultrafilterable calcium in maternal and fetal plasmas

Cited by 82 publications

References 0 publications

Bone Development and Mineral Homeostasis in the Fetus and Neonate: Roles of the Calciotropic and Phosphotropic Hormones

Bone Development and Mineral Homeostasis in the Fetus and Neonate: Roles of the Calciotropic and Phosphotropic Hormones

Calcium Uptake and Binding by Membrane Fractions of Human Placenta: ATP-dependent Calcium Accumulation

Parathormone and Perinatal Calcium Homeostasis

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