Expression Of Atrial Natriuretic Peptides And Its Receptors In Rat Cochlea Stria Vascularis Marginal Cells Of Primary Culture

Objective: The purpose of this study was to investigate the expression of atrial natriuretic peptides (ANP) and its receptors in rat cochlea stria vascularis marginal cells (MC) of primary culture.Methods: Strial vascularis tissues of newborn rats were isolated by mechanical dissociation. The explants were grown on sterilized disposable plastic dishes with 35mm diameters, cultured in Minimum essential medium (MEM) containing 20% fetal bovine serum (FBS), Epidermal growth factor (EGF), Hydrocortisone, Triiodothronine, Insulin- Transferrin-Sodium. Cultures were kept at 37℃in a 5% CO2/95%O2 air incubator and observed daily by inverted microscope. The culture medium was changed twice a week or according to the cells growth conditions. Cultured cells were examined and photographed using an inverted microscope. Immunocytochemical method was used to identify the origin of MC. The expression of ANP and its receptors in MC were examined with immunohistochemical method and reverse-transcription polymerase chain reaction (RT-PCR) technique.Results: MC grew out of the explants usually at 2nd culture day, and has polygonal appearance, big and round nucelus. MC may grow into monolayer, "cobblestone-like" appearance. The cultured MC expressed cytokeratin 18, which indicated the epithelial origination of MC. Immunohistochemical method and RT-PCR showed that ANP and its receptors were expressed in MC.Conclusions: The primary culture system of the marginal cells was successfully established. MC in vitro has the same morphologic characteristics as MC in vivo.The expression of ANP and its receptors in MC of primary culture suggested that ANP may play an important role in moderating inner microenvironment by regulating the function of MC. It may be a suitable model for an in-depth investigation of the function of ANP in MC.