Electrogenic ion transport in the mouse endometrium: functional aspects of the cultured epithelium

Abstract

A primary culture of mouse endometrial epithelium grown on permeable supports 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 immunostained with epithelial cells markers, cytokeratins, indicating an epithelial origin of the culture. Mouse endometrial epithelial cells grown on Millipore filters formed polarized monolayers with junctional complexes as revealed by light and electron microscopy. The cultured monolayers exhibited an average basal I(SC) of 4.6 +/- 0.3 microA/cm2, transepithelial voltage of 2.7 +/- 0.2 mV and transepithelial resistance of 599 +/- 30 omega cm2. The basal current was reduced by 85% in Na+-free solution and 13% in Cl(-)-free solution. The basal current could also be substantially (57.7%) blocked by an apical Na+ channel blocker, amiloride (10 microM), suggesting that Na+ absorption largely contributed 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 increases in the I(SC), which could involve substantial Cl- secretion. The present study has established a culture of mouse endometrial epithelium exhibiting predominantly Na+ absorption under unstimulated condition, and Cl- secretion in response to various secretagogues. This culture may be useful for studying various regulatory mechanisms of electrogenic ion transport across the endometrial epithelium.

Suppression of CFTR-Mediated Cl− Secretion by Enhanced Expression of Epithelial Na+ Channels in Mouse Endometrial Epithelium

“…Previous studies have shown that cultured endometrial epithelia exhibit a basal Isc which is predominantly amiloride-sensitive, indicative of Na ϩ absorption which could be switched to predominant CFTRmediated anion secretion upon stimulation (10,16,17). In the present study, variations in basal Isc were observed for different batches of cultured endometrial epithelia.…”

“…Endometrial epithelial cells were enzymatically isolated from the mouse uterus according to the method described by McCormack and Glasser (9) with slight modifications (10). The isolated endometrial cells were plated on nitrocellulose Millipore filters (0.45 cm 2 ) without or with Matrigel coating.…”

Inhibition of amiloride-sensitive Na + absorption by activation of CFTR in mouse endometrial epithelium

“…Endometrial epithelial cells were isolated enzymatically from the mouse uterus according to [15] with slight modifications [5]. Uteri were obtained from 3.5-to 4-week-old immature ICR mice to avoid the complication of the oestrous cycle.…”

“…Recent studies on primary cultures of mouse endometrial epithelium have demonstrated predominantly Na + absorption under basal conditions but mostly anion secretion upon stimulation [4,5,6,9]. Cultured endometrial epithelium responds to adrenaline, noradrenaline, prostaglandin E 2 (PGE 2 ) or forskolin with an increase in the short-circuit current (I sc ) that can be attributed predominantly to Cl -and HCO 3 -secretion.…”

Enhanced Epithelial Na+ Channel (ENaC) Activity in Mouse Endometrial Epithelium by Upregulation of .GAMMA.ENaC Subunit.

“…Increased ENaC activity by culture conditions. Previous studies have shown that cultured endometrial epithelia exhibit a basal I SC that can be effectively blocked by amiloride, indicative of predominant Na ϩ absorption [10,13]. We recently found that the ENaC activity of endometrial cultures could be affected by coating the permeable support with Matrigel [14], which resembles the extracellular matrix facilitating rapid epithelial reconstitution and differentiation [15,16].…”