The human kidneys produce approximately 160-170 L of ultrafiltrate per day. The proximal tubule contributes to fluid, electrolyte, and nutrient homeostasis by reabsorbing approximately 60%-70% of the water and NaCl, a greater proportion of the NaHCO3, and nearly all of the nutrients in the ultrafiltrate. The proximal tubule is also the site of active solute secretion, hormone production, and many of the metabolic functions of the kidney. This review discusses the transport of NaCl, NaHCO3, glucose, amino acids, and two clinically important anions, citrate and phosphate. NaCl and the accompanying water are reabsorbed in an isotonic fashion. The energy that drives this process is generated largely by the basolateral Na(+)/K(+)-ATPase, which creates an inward negative membrane potential and Na(+)-gradient. Various Na(+)-dependent countertransporters and cotransporters use the energy of this gradient to promote the uptake of HCO3 (-) and various solutes, respectively. A Na(+)-dependent cotransporter mediates the movement of HCO3 (-) across the basolateral membrane, whereas various Na(+)-independent passive transporters accomplish the export of various other solutes. To illustrate its homeostatic feat, the proximal tubule alters its...Continue Reading
Microelectrode determination of pH and PCO2 in rat proximal tubule after benzolamide: evidence for hydrogen ion secretion
Carrier-mediated transfer of D-glucose in brush border vesicles derived from rabbit renal tubules. Na+-dependent versus Na+-independent transfer
Dose-dependent stimulation and inhibition of proximal tubular sodium reabsorption by angiotensin II in the rat kidney
Preincubation in acid medium increases Na/H antiporter activity in cultured renal proximal tubule cells
Chronic metabolic acidosis causes an adaptation in the apical membrane Na/H antiporter and basolateral membrane Na(HCO3)3 symporter in the rat proximal convoluted tubule
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Tubular reabsorption of L-glutamine studied by free-flow micropuncture and microperfusion of rat kidney
Comparative effects of dietary phosphate, unilateral nephrectomy, and parathyroid hormone on phosphate transport by the rabbit proximal tubule
Endothelin's biphasic effect on fluid absorption in the proximal straight tubule and its inhibitory cascade
Identification of an mRNA-binding protein and the specific elements that may mediate the pH-responsive induction of renal glutaminase mRNA
Immunocytochemical localization of a high-affinity glutamate-aspartate transporter, GLAST, in the rat and guinea-pig cochlea
Cellular mechanisms involved in the acute adaptation of OK cell Na/Pi-cotransport to high- or low-Pi medium
Identification and characterization of a membrane protein (y+L amino acid transporter-1) that associates with 4F2hc to encode the amino acid transport activity y+L. A candidate gene for lysinuric protein intolerance
Regulation of expression of the SN1 transporter during renal adaptation to chronic metabolic acidosis in rats
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Induction and targeting of the glutamine transporter SN1 to the basolateral membranes of cortical kidney tubule cells during chronic metabolic acidosis suggest a role in pH regulation
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Evidence for a signaling axis by which intestinal phosphate rapidly modulates renal phosphate reabsorption
Renal phosphaturia during metabolic acidosis revisited: molecular mechanisms for decreased renal phosphate reabsorption
FGF23 decreases renal NaPi-2a and NaPi-2c expression and induces hypophosphatemia in vivo predominantly via FGF receptor 1
Role of AUF1 and HuR in the pH-responsive stabilization of phosphoenolpyruvate carboxykinase mRNA in LLC-PK₁-F⁺ cells
Proteomic profiling of the effect of metabolic acidosis on the apical membrane of the proximal convoluted tubule
Mitochondrial aquaporin-8 in renal proximal tubule cells: evidence for a role in the response to metabolic acidosis
Response of the mitochondrial proteome of rat renal proximal convoluted tubules to chronic metabolic acidosis
Knockout of Na-glucose transporter SGLT2 attenuates hyperglycemia and glomerular hyperfiltration but not kidney growth or injury in diabetes mellitus
Fibroblast growth factor 23 and Klotho: physiology and pathophysiology of an endocrine network of mineral metabolism
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Chronic metabolic acidosis reduces urinary oxalate excretion and promotes intestinal oxalate secretion in the rat
Uroguanylin modulates (Na++K+)ATPase in a proximal tubule cell line: Interactions among the cGMP/protein kinase G, cAMP/protein kinase A, and mTOR pathways
Adiponectin, Leptin, and Fatty Acids in the Maintenance of Metabolic Homeostasis through Adipose Tissue Crosstalk
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HK2 Proximal Tubule Epithelial Cells Synthesize and Secrete Plasma Proteins Predominantly Through the Apical Surface
Nonmuscle myosin 2 proteins encoded by Myh9 , Myh10 , and Myh14 are uniquely distributed in the tubular segments of murine kidney
Exocrine pancreas glutamate secretion help to sustain enterocyte nutritional needs under protein restriction
Dietary Potential Renal Acid Load Is Positively Associated with Serum Uric Acid and Odds of Hyperuricemia in the German Adult Population
A Non-Targeted Capillary Electrophoresis-Mass Spectrometry Strategy to Study Metabolic Differences in an In vitro Model of High-Glucose Induced Changes in Human Proximal Tubular HK-2 Cells
Did Acidic Stress Resistance in Vertebrates Evolve as Na+ /H+ Exchanger-Mediated Ammonia Excretion in Fish?
Low urine pH predicts new onset of diabetes mellitus during a 10-year period in male subjects: BOREAS-DM1 Study
Acetazolamide causes renal [Formula: see text] wasting but inhibits ammoniagenesis and prevents the correction of metabolic acidosis by the kidney
Hypoxia-mediated regulation of mitochondrial transcription factors in renal epithelial cells: implications for hypertensive renal physiology
NRF2 regulates the glutamine transporter Slc38a3 (SNAT3) in kidney in response to metabolic acidosis
Triterpene derivative improves the renal function of streptozotocin-induced diabetic rats: a follow-up study on maslinic acid
Long-term in vitro effects of exposing the human HK-2 proximal tubule cell line to 3-monochloropropane-1,2-diol
Hnf4a Is Required for the Development of Cdh6-Expressing Progenitors into Proximal Tubules in the Mouse Kidney
Estimates of renal net acid excretion and their relationships with serum uric acid and hyperuricemia in a representative German population sample
Tubulointerstitial nephritis-induced hypophosphatemic osteomalacia in Sjögren's syndrome: a case report and review of the literature
Effects of dietary electrolyte balance and calcium supply on mineral and acid-base status of piglets fed a diversified diet
Proximal tubule-specific glutamine synthetase deletion alters basal and acidosis-stimulated ammonia metabolism
Defining the short-term effects of pharmacological 5'-AMP activated kinase modulators on mitochondrial polarization, morphology and heterogeneity
Magnesium, Calcium, Potassium, Sodium, Phosphorus, Selenium, Zinc, and Chromium Levels in Alcohol Use Disorder: A Review
Low potassium diets with different levels of calcium in comparison with different anionic diets fed to prepartum dairy cows: Effects on sorting behaviour, total tract digestibility, energy metabolism, oxidative status and hormonal response
HIF-1α and HIF-2α differently regulate tumour development and inflammation of clear cell renal cell carcinoma in mice
Phosphoenolpyruvate carboxykinase in urine exosomes reflect impairment in renal gluconeogenesis in early insulin resistance and diabetes
Predicting the protein composition of human urine in normal and pathological states: quantitative description based on dent1 disease (CLCN5 mutation)
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