Effects of non-steroidal estrogen diethylstilbestrol on pH and ion transport in the mantle epithelium of a bivalve Anodonta cygnea

• DES modulates ion transport and intracellular pH in Outer Mantle Epithelium (OME) of Anodonta cygnea.
• DES exposure decreases OME short-circuit current.
• DES acts in basolateral membrane by inhibition of HCO3−/Cl− co-transporters.

Freshwater bivalves are used as sentinel organisms to detect pollutants effects in the aquatic environment due to their sedentary nature, filter-feeding behaviour. We aimed to determine the in vivo, ex vivo and in vitro influence of Diethylstilbestrol (DES), a widely used synthetic non-steroidal estrogen and endocrine disruptor, in Anodonta cygnea shell growth mechanisms. For that, in vivo exposure to DES (0.75 μM) during 15 days, in vitro and ex vivo exposure of outer mantle epithelium (OME) cells to DES (0.75 μM), were performed followed by study of short-circuit current (Isc), transepithelial potential (Vt) and transepithelial conductance (Gt) as well as identification of membrane transport systems and intracellular pH (pHi). Our results show that in vivo exposure to DES decreases in 30% the OME Isc and ex vivo addition of DES to the basolateral side of OME also induced Isc decrease. Several membrane transporters such as V-type ATPases, Na+/H+ exchangers, Na+–K+ pump, Na+-driven and Na+-independent HCO3−/Cl− transporters and Na+/HCO3− co-transporter were identified as responsible for pHi maintenance in OME and noteworthy, DES caused a pHi decrease in OME cells similar to the effect observed when OME cells were exposed to 4,4′-diisothiocyanostilbene disulfonic acid (DIDS), an inhibitor of several bicarbonate membrane transporters. The addition of DIDS after OME cells exposure to DES did not cause any alteration. We concluded that DES is able to modulate membrane ion transport and pHi in the OME of A. cygnea and that this effect seems to be due to inhibition of HCO3−/Cl− co-transporters present on the basolateral membrane.