( ( ( The ( intracellular pH ) ) ( of ( ( ( ( the ( proximal ( tubule cells ) ) ) and ) ( , ( thereby ( , ( ( the OH ) - ) ) ) ) ) gradient ) ) ) ( ( is ( maintained ( by ( ( the ( luminal ( sodium-proton exchanger ) ) ) ( -LRB- ( NHE3 -RRB- ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN intracellular) (NN pH)) (PP (IN of) (NP (NP (DT the) (JJ proximal) (JJ tubule) (NNS cells)) (CC and) (PRN (, ,) (ADVP (RB thereby)) (, ,) (NP (DT the) (NNP OH)) (: -)) (NP (NN gradient))))) (VP (VBZ is) (VP (VBN maintained) (PP (IN by) (NP (NP (DT the) (JJ luminal) (JJ sodium-proton) (NN exchanger)) (PRN (-LRB- -LRB-) (NP (NNP NHE3)) (-RRB- -RRB-)))))) (. .)))
The intracellular pH of the proximal tubule cells and, thereby, the OH- gradient is maintained by the luminal sodium-proton exchanger (NHE3).
(ROOT (S (NP (NP (NNP Processing)) (PP (IN of) (NP (NP (NN filtrate)) (PP (IN in) (NP (DT the) (JJ proximal) (NN tubule)))))) (VP (VBZ helps) (VP (VB maintain) (NP (DT the) (NN ph) (NN level)) (PP (IN in) (NP (NN body) (NN fluid))))) (. .)))