A novel technique for studying cellular function in human placenta: gestational changes in intracellular pH regulation.
This paper presents a new method for the study of cell function in primary human placental syncytiotrophoblast cells. Chorionic villous tissue fragments from term and first trimester placenta were loaded with fluorescent pH sensitive indicator dye HPTS and made adherent to a microscope cover-slip. The fragments were superfused and intracellular pH (pHi) was studied by microfluorimetry. We used this new methodology to examine the role of the Na+/H+ antiporter in pHi regulation. Syncytial cells demonstrated homeostatic pHi regulation, recovering back to basal pHi after intracellular acidification. In the absence of HCO3-, the Na+/H+ antiporter was the primary means by which syncytiotrophoblast cells recovered from an intracellular acid load in both term and first trimester samples. The rate of recovery from intracellular acidification showed a strong correlation to degree of acidification, confirming allosteric modification of antiporter activity by intracellular protons. The transporter was regulated by phosphorylation mediated by protein kinase C (PKC) at both gestational ages. This methodology represents a powerful new technique for the study of syncytiotrophoblast cell ionic regulation.
Department of Obstetrics and Gynecology, University of California, San Francisco 94143-0550, USA.
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Powell
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Illsley
D005260:Female; D005865:Gestational Age; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008856:Microscopy, Fluorescence; D010766:Phosphorylation; D011247:Pregnancy; D011493:Protein Kinase C / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism; D014327:Trophoblasts / Q000166:cytology* / Q000502:physiology*
D017923:Sodium-Hydrogen Exchangers; D011493:Protein Kinase C