... cell to lumen via the antiporter even though the pH in the bulk fluid of the lumen is highly alkaline. Exchange of outer bulk fluid K + (or Na + ) with outer interface H + in conjunction with (K + or Na + )/2H + antiport, transforms the hydrogen ion electrochemical potential difference, \batchmode...

... ) and intracellular activities of K + ( a K i ) and Cl – ( a Cl i ). Calculation of the electrochemical potentials for both ions permitted assessment of the possible contributions of K + channels, Na + :K + :2Cl – cotransport, and K + :Cl – cotransport, to net transepithelial ion secretion across the basolateral...

... and -63mV for unstimulated and stimulated tubules, respectively. Calculated electrochemical potentials(Δμ/ F ) favour passive movement of Na + into the cell and passive movement of Cl - out of the cell in both unstimulated and serotonin-stimulated tubules. Passive movement of K + out of the cell is favoured...