Artículos de revistas
The Maxi-Chloride Channel in Human Syncytiotrophoblast: A Pathway for Taurine Efflux in Placental Volume Regulation?
Fecha
2007Registro en:
Placenta 28 (2007), 1182-1191
doi:10.1016/j.placenta.2007.06.005
Autor
Vallejos, C.
Riquelme Pino, Gloria
Institución
Resumen
Taurine (Tau), the most abundant amino acid in fetal blood, is highly concentrated in human placenta. During pregnancy, Tau is involved in
the neurological development of the fetus, and in volume regulation of the placenta. The placenta may release taurine in parallel with Kþ
and Cl in response to an increase in cell volume. However, the pathway for the volume-activated taurine efflux is unknown. One candidate
is a voltage-dependent Maxi-chloride channel from apical syncytiotrophoblast membrane (MVM), with a conductance over 200 pS and multiple
subconductance states. Our aim was to study whether this channel could be a Tau conductive pathway in the MVM. Purified human placental
MVM were reconstituted into giant liposomes suitable for patch clamp recordings. Typical Maxi-chloride channel activity was detected in symmetrical
chloride (Cl ) solutions, and then taurine (Tau), Aspartate (Asp), and glutamate (Glu) solutions were used in the bath of excised patches
to detect single channel currents carried by these anions. The relative permeabilities (P), estimated from the shift in reversal potential of currentvoltage
curves after anion replacement, were as follows: Chloride > Taurine ¼ Glutamate ¼ Aspartate. In Tau symmetric conditions using
equivalent Cl concentrations, the slope conductance was 62.4 7.3 pS. The data shows that Tau and other amino acids diffuse through the
Maxi-chloride channel, which could be of great importance as part of the mechanism involved in the volume regulation process in human
placenta.