Coupling of Na+/α-ketoglutarate symport and PAH/α-ketoglutarate antiport in epithelial cells. Estimation of probability of the anion exchanger spontaneous re-orientation

In this work, dynamics of uptake ofp-aminohippurate (PAH) by basolateral membrane vesicles isolated from rat kidney proximal tubules was studied. The uphill PAH transport into the basolateral membrane vesicles in the presence of alpha-ketoglutarate and Na+-gradient was shown. Based on mathematical model of symport and antiport cooperation the mechanism of energy coupling of PAH transport by the way of exchanger with Na+-dicarboxylate symport is discussed. Based on comparison of our own and literature data, the data analysis shows adequacy of the proposed mathematical model to describe the symport and antiport cooperation. This model was demonstrated to enable estimation of re-orientation probability of the empty anion exchanger (without substrate) from one membrane side to the other.