Extracellular ATP stimulates estradiol secretion in rat Sertoli cells in vitro: modulation by external sodium

In this study, we examined the effects of extracellular ATP (ATPe) on [Ca2+]i, [Na+]i, plasma membrane potential changes and estradiol secretion in rat Sertoli cells. ATPe caused a rapid rise of [Ca2+]i with an initial spike followed by a long lasting plateau. The first rapid spike was dependent on the release of Ca2+ from internal stores as it also occurred in Ca2+-free medium while the long lasting plateau phase was dependent on Ca2+ influx from the external medium. ATPe stimulated a rapid plasma membrane depolarization that was dependent on an influx of Na+ from the external medium as demonstrated by plasma membrane potential monitoring in Na+-free medium and by [Na+]i measurement with the Na+-sensitive fluorescent dye SBFI. ATPe stimulated estradiol secretion in a dose dependent manner and was fully dependent on the presence of Na+ in the external medium while the presence of Ca2+ was not necessary. Among the different nucleotides tested, only ATP, ATP-5′-[γ-thio]triphosphate, UTP, α,β-methylene-ATP were effective in stimulating estradiol secretion. These results demonstrate that rat Sertoli cells possess P2-purinergic receptors belonging to the P2X and P2Y subfamily which activation induces [Ca2+]i and [Na+]i rise and Na+-dependent plasma membrane depolarization leading to estradiol secretion. Copyright © 2001 Elsevier Science Ireland Ltd.