Isolation and partial characterization of the basal cell membrane of human placental trophoblast

Kelley, Lucky K.; Smith, Carl H.; King, Barry F.

doi:10.1016/0005-2736(83)90079-2

Cited by 133 publications

(55 citation statements)

References 40 publications

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“…This generates an inwardly directed Na + gradient which in turn facilitates the Na + entry mechanisms. In the placenta, this transporter was originally thought to be located predominantly on the BM (Kelley et al, 1983) as in other epithelia but, a more recent, thorough study showed that both expression and activity of Na + /K + /ATPase is present on the MVM at levels twice that of the BM (Johansson et al, 2000). Na + /K + /ATPase activity is relatively low in the placenta compared to other transporting epithelia (Birdsey et al, 1997) and it does not contribute significantly to E m in cytotrophoblast cells or intact syncytiotrophoblast (Birdsey et al, 1997).…”

Section: Na + /K + /Atpasementioning

confidence: 99%

Placental nutrient supply and fetal growth

Desforges¹,

Sibley²

2010

Int. J. Dev. Biol.

146

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This review considers mechanisms by which transfer across the placenta takes place and how the capacity of the placenta to supply nutrients relates to fetal growth and vice versa. Blood flow through both uterine and umbilical circulations of the placenta, the structural properties of the placental exchange barrier and its related diffusional permeability, and the expression and activity of a wide range of transporter proteins in the syncytiotrophoblast, the transporting epithelium of the placenta, all need to be taken into account in considering placental supply capacity. We discuss the evidence that each of these factors affects, and is affected by, fetal growth rate and consider the regulatory mechanisms involved, with a particular focus on data that has emerged from study of the system A amino acid transporter. We consider that future work will build on the considerable foundation of knowledge regarding placental transfer mechanisms, as well as the other aspects of placental structure and function, to develop new diagnostic and therapeutic strategies for pregnancy complications, such as fetal growth restriction or overgrowth.

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Section: Na + /K + /Atpasementioning

confidence: 99%

Placental nutrient supply and fetal growth

Desforges¹,

Sibley²

2010

Int. J. Dev. Biol.

146

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“…5). This 1 1 GLU CI 12 Sec 30 sec Flpre 5. Effect of anion species on initial uptake (12 and 30 s) of 10 pM "Ca2+ by Na+/Ca2+ exchange.…”

Section: Resultsmentioning

confidence: 86%

“…The syncytial basal membrane itself has both folded and smooth portions that may be functionally different (31). Furthermore, the isolated preparation very likely includes some cytotrophoblast plasma membrane that adheres to the basal lamina (12). Thus, the Na+/ca2+ exchange mechanism may be present in only a particular portion of the membrane composing the isolated preparation and in that portion may have a capacity substantially higher than the measured overall V, , .…”

Section: Discussionmentioning

confidence: 99%

“…The basal membrane vesicles used in this report were 44-2 Ifold (n = 9) enriched in dihydroalprenolol binding, the marker for basal membranes (12), and less than 1-fold enriched for alkaline phosphatase activity, the marker for MVM (15). The BPM vesicles are mixed in orientation, with substantial fractions of the vesicles oriented right-side out (cytoplasmic side on the inside of the vesicles) and inside-out (16).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Na+/Ca2+ Exchange, Ca2+ Binding, and Electrogenic Ca2+ Transport in Plasma Membranes of Human Placental Syncytiotrophoblast

Kamath

Smith

1994

Pediatr Res

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To transfer a large amount of CaZ+ to the fetus, the basal (fetal-facing) plasma membrane (BPM) of human placenta must be equipped with various extrusion mechanisms. We studied one such mechanism, Na+/Ca2+ exchange, as well as related membrane potential effects and binding properties of the two membranes. Na+/Ca2+ exchange was present in BPM and absent in microvillous (maternal-facing) membrane. Uptake and efflux of Ca2+ in BPM were enhanced by Na+ when it was present on the opposite side of the membranes. Na+-gradient-dependent Ca2+ uptake was saturable with a Km of 19 FM and a V , , of 0.8 nmol/min/mg. The Na+/Ca2+ exchange in BPM and the facilitated difhsion transporters in both BPM and miThe human placental syncytiotrophoblast is the major bamer to the passage of ca2+ ions from the mother to the fetus (1). specific transport mechanisms in the microvillous (maternal-facing) and basal (fetal-facing) membranes of syncytiotrophoblast mediate the transfer of ca2+ across the placenta. While providing for the transplacental passage of large amounts of Ca2+, the syncytiotrophoblast must also maintain intrasyncytial free ca2+ concentrations several orders of magnitude lower than those in the plasma or extracellular fluid (2). To achieve this, one or both of its plasma membranes must possess energydependent extrusion mechanisms such as an ATPdependent Ca2+ pump or an ~a + /~a~+ exchange mechanism. The higher concentration of ca2+ in the fetal circulation (1) suggests the presence of such extrusion mechanisms in the basal membrane.Several investigators have attempted to characterize ATP-dependent ca2+ transport mechanisms of mem- branes from human placenta and other cell types (3-7). Our laboratory (3) has demonstrated ATP-dependent Ca2+ uptake in the basal membranes at nanomolar concentrations of free ca2+. We (8, 9) and others (10,11) have demonstrated the presence of facilitated diffusion transporters in both BPM and MVM.We now report the presence of an ~a + /~a~+ extrusion mechanism in basal membrane isolated from term human placentas. We investigated the effect of Na+ on ca2+ entry and binding in the microvillous and the basal membranes and also the effect of membrane potential on plasma membrane ca2+ transfer processes.

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“…Transport and metabolism of adenosine has been demonstrated at maternal and fetal blood-tissue interfaces of the perfused guinea-pig placenta (Wheeler & Yudilevich, 1988). We have now measured the binding of [3H]NBMPR to human placental membrane vesicles prepared by standard procedures (Glazier et al 1988;Kelley et al 1983) from the maternal (brush-border) and fetal (basal) The apical membrane of the diluting segment of both amphibians and mammals contains a potassium conductance which allows potassium to leak out of the cell into the tubule lumen (Guggino et al 1988). Potassium re-enters the cell via an electroneutral co-transporter with one sodium and two chloride ions.…”

Section: Pmentioning

confidence: 99%

Proceedings of the Physiological Society, 21‐22 July 1989, Cambridge Meeting: Poster Communications

1989

The Journal of Physiology

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Isolation and partial characterization of the basal cell membrane of human placental trophoblast

Cited by 133 publications

References 40 publications

Placental nutrient supply and fetal growth

Placental nutrient supply and fetal growth

Na+/Ca2+ Exchange, Ca2+ Binding, and Electrogenic Ca2+ Transport in Plasma Membranes of Human Placental Syncytiotrophoblast

Proceedings of the Physiological Society, 21‐22 July 1989, Cambridge Meeting: Poster Communications

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