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Endothelin-1 blunts transepithelial transport and differentiation of Madin-Darby canine kidney cells
L Wojnowski1, B Gassner, W Steigner
1Department of Physiology, University of Würzburg, Federal Republic of Germany.
Abstract:
We investigated the effects of endothelin-1 (ET-1) on Madin-Darby canine kidney (MDCK) cells, a cell line originating from the renal collecting duct. The activity of transepithelial transport was assessed as the rate of dome formation in monolayers grown on solid support. The pH value of the dome fluid (dome pH) was measured by means of pH-selective microelectrodes. Differentiation of monolayer cells was estimated as the peanut-lectin(PNA)-binding capacity of the apical membrane. Confluent monolayers were incubated for 12-72 h in serum-free medium at various concentrations of ET-1. Exposure to 1 nmol/l ET-1 reduced dome formation by a maximum of 41 +/- 8% (n = 4; P less than 0.02) after 24 h. ET-1 (10 nmol/l; 24 h) decreased dome pH from 7.52 +/- 0.02 (n = 53) to 7.36 +/- 0.03 (n = 51; P less than 0.02). Apical application of amiloride (1 mmol/l) reduced dome pH in both ET-1-treated and non-treated domes to essentially the same level, 7.25 +/- 0.03 (n = 19) and 7.23 +/- 0.03 (n = 17) respectively. ET-1 (10 nmol/l; 24 h) reduced PNA-binding capacity by 19 +/- 3% (n = 5; P less than 0.02). Moreover, ET-1 prevented the increase in PNA binding (+ 53 +/- 7%; n = 5) induced by 0.1 mumol/l aldosterone. We conclude that ET-1 inhibits transepithelial transport and PNA binding via inhibition of apical Na+/H+ exchange, thus antagonizing aldosterone action in MDCK cells.
Insights
Endothelin-1 (ET-1) inhibits transepithelial transport and cell differentiation in Madin-Darby canine kidney (MDCK) cells. This peptide antagonizes aldosterone action by inhibiting apical Na+/H+ exchange.
Area of Science:
- Nephrology
- Cell Biology
- Molecular Pharmacology
Background:
- Madin-Darby canine kidney (MDCK) cells are a widely used model for studying renal collecting duct function.
- Endothelin-1 (ET-1) is a potent vasoconstrictor peptide with known roles in renal physiology.
- The regulation of transepithelial transport and cell differentiation in kidney cells is crucial for maintaining renal homeostasis.
Purpose of the Study:
- To investigate the effects of endothelin-1 (ET-1) on transepithelial transport and cell differentiation in MDCK cells.
- To elucidate the mechanism by which ET-1 influences these cellular processes.
- To determine if ET-1 antagonizes the action of aldosterone in MDCK cells.
Main Methods:
- MDCK cell monolayers were cultured and treated with various concentrations of ET-1.
- Transepithelial transport was assessed by measuring dome formation and dome fluid pH using pH-selective microelectrodes.
- Cell differentiation was evaluated by quantifying peanut-lectin (PNA)-binding capacity of the apical membrane.
Main Results:
- ET-1 significantly reduced dome formation and dome fluid pH in MDCK cell monolayers.
- ET-1 decreased PNA-binding capacity, indicating reduced cell differentiation.
- ET-1 inhibited the aldosterone-induced increase in PNA binding, suggesting antagonism of aldosterone action.
Conclusions:
- ET-1 inhibits transepithelial transport in MDCK cells, likely by inhibiting apical Na+/H+ exchange.
- ET-1 impairs cell differentiation and antagonizes aldosterone's effects on MDCK cells.
- These findings highlight a novel role for ET-1 in regulating renal collecting duct cell function.