ELECTROGENIC ION-TRANSPORT IN THE MOUSE ENDOMETRIUM - FUNCTIONAL-ASPECTS OF THE CULTURED EPITHELIUM

A primary culture of mouse endometrial epithelium grown on permeable s upports was established and the electrogenic ion transport across the endometrial epithelium was studied using the short-circuit current (I- SC) technique. Enzymatically isolated mouse endometrial cells were imm unostained with epithelial cells markers, cytokeratins, indicating an epithelial origin of the culture. Mouse endometrial epithelial cells g rown on Millipore filters formed polarized monolayers with junctional complexes as revealed by light and electron microscopy. The cultured m onolayers exhibited an average basal I-SC of 4.6 +/- 0.3 mu A/cm(2), t ransepithelial voltage of 2.7 +/- 0.2 mV and transepithelial resistanc e of 599 +/- 30 Omega cm(2). The basal current was reduced by 85% in N a+-free solution and 13% in Cl--free solution. The basal current could also be substantially (57.7%) blocked by an apical Na+ channel blocke r, amiloride (10 mu M), suggesting that Na+ absorption largely contrib uted to the basal current. Apical addition of Cl- channel blocker, DPC (2 mM), also exhibited an inhibitory effect. 19.4%, on the basal I-SC , indicating minor involvement of Cl- secretion as compared to that of Na+ absorption. The cultured endometrial epithelium also responded to a number of secretagogues including adrenaline and forskolin with inc reases in the I-SC, which could involve substantial Cl- secretion. The present study has established a culture of mouse endometrial epitheli um exhibiting predominantly Na+ absorption under unstimulated conditio n, and Cl- secretion in response to various secretagogues. This cultur e may be useful for studying various regulatory mechanisms of electrog enic ion transport across the endometrial epithelium.