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 pri mary human placental syncytiotrophoblast cells. Chorionic villous tiss ue fragments from term and first trimester placenta were loaded with f luorescent pH sensitive indicator dye HPTS and made adherent to a micr oscope cover-slip. The fragments were superfused and intracellular pH (pH(i)) was studied by microfluorimetry. We used this new methodology to examine the role of the Na+/H+ antiporter in pH(i) regulation. Sync ytial cells demonstrated homeostatic pH(i) regulation, recovering back to basal pH(i) after intracellular acidification. In the absence of H CO3-, the Na+/H+ antiporter was the primary means by which syncytiotro phoblast cells recovered from an intracellular acid load in both term and first trimester samples. The rate of recovery from intracellular a cidification showed a strong correlation to degree of acidification, c onfirming allosteric modification of antiporter activity by intracellu lar 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 syncytiotrophobla st cell ionic regulation. (C) 1996 W. B. Saunders Company Ltd