Relationship between intracellular pH and ammonia metabolism in LLC-PK1 cells

1990 ◽  
Vol 258 (1) ◽  
pp. F103-F108 ◽  
Author(s):  
A. Sahai ◽  
E. Laughrey ◽  
R. L. Tannen
Keyword(s):  
Intracellular Ph ◽  
Cultured Cells ◽  
Ph Responsive ◽  
Bicarbonate Concentration ◽  
Acid Base ◽  
Ammonia Metabolism ◽  
Ph Changes ◽  
Concentration Measurements ◽  
Significant Change ◽  
Alanine Production

Previous studies from our laboratory have confirmed that cultures of LLC-PK1 cells exhibit pH-responsive alterations in ammonia metabolism produced by changes in media bicarbonate concentration. To further elucidate the mechanism of ammonia regulation, studies were carried out using parallel cultures of still and rocked LLC-PK1 cells subjected to acute alterations in media pH by either metabolic or respiratory acid-base manipulations. When media pH was altered by modifying PCO2 levels, the response of ammonia and alanine production by rocked culture was identical to the changes observed with metabolic acid-base maneuvers. Furthermore, both metabolic and respiratory acute acidosis resulted in a fall of intracellular alpha-ketoglutarate concentrations in these cells. In contrast, standard still cultures subjected to acute acidosis/alkalosis by metabolic and respiratory manipulations did not exert any significant change in ammonia and alanine production or in intracellular alpha-ketoglutarate concentration. Measurements of intracellular pH (pHi) by the 5,5-[2-14C]dimethyloxazolidine-2,4-dione method in rocked cells demonstrated changes in pHi parallel to media pH changes induced by both metabolic and respiratory acid-base maneuvers. Despite the absence of pH-responsive ammonia-genesis in still cultured cells the pHi values were altered in a fashion similar to their rocked counterparts, indicating the lack of an effect of the pHi signal on ammonia metabolism.

Intracellular and extracellular acid-base regulation in the tropical fresh-water teleost fish Synbranchus marmoratus in response to the transition from water breathing to air breathing

1982 ◽  
Vol 99 (1) ◽  
pp. 9-28 ◽  
Author(s):  
N. Heisler
Keyword(s):  
Partial Pressure ◽  
Fresh Water ◽  
Intracellular Ph ◽  
Environmental Water ◽  
Fresh Water Fish ◽  
Bicarbonate Concentration ◽  
Acid Base ◽  
Intracellular Space ◽  
Air Breathing ◽  
Main Site

In the tropical fresh water fish, Synbranchus marmoratus, transition from water breathing to air breathing, induced by reduction of oxygen partial pressure (PO2) in the environmental water below 16 mmHg, causes a considerable rise in the arterial partial pressure of carbon dioxide (PCO2), from 5.6 to 26 mmHg on the average (half time of the rise between 2 and 6.5 h). The associated fall in arterial plasma pH by about 0.6 units is not compensated by an increase in plasma bicarbonate concentration, whereas the intracellular pH of white skeletal muscle and heart muscle is kept almost constant by elevation of the intracellular bicarbonate concentration. The additional bicarbonate is generated by intracellular non-bicarbonate buffering, and by net transfer into the intracellular space of bicarbonate formed by buffering in blood. Only a relatively small quantity of bicarbonate is taken up from environmental water. This type of acid-base regulation, with almost complete intracellular pH compensation and only minor bicarbonate uptake (equivalent H+ release or OH- uptake) from water, is attributed to several factors. Probably the most important of these is the lack of continuous contact of the gills, which are the main site of ion transfer processes, with the environmental water during air breathing. Regardless of the mechanisms involved, this particular strategy of acid-base regulation provides a constant milieu for the intracellular structures and demonstrates the prevalence of intracellular over extracellular acid-base regulation.

The Intracellular pH of Human Leucocytes in Response to Acid—Base Changes in Vitro

1976 ◽  
Vol 50 (4) ◽  
pp. 293-299 ◽  
Author(s):  
G. E. Levin ◽  
P. Collinson ◽  
D. N. Baron
Keyword(s):  
Metabolic Acidosis ◽  
Intracellular Ph ◽  
Metabolic Alkalosis ◽  
Venous Blood ◽  
Bicarbonate Concentration ◽  
Acid Base ◽  
Ph Measurements

1. Viable human leucocytes were isolated from venous blood and suspended in artificial media. Intracellular pH measurements were made by the dimethyloxazolidinedione technique in conditions simulating ‘respiratory’ or ‘metabolic’ acid-base disturbances. 2. Normal intracellular pH was 7·11 ± 0·02 (mean ± 2 sd) at an extracellular Pco2 of 5·8 kPa and a bicarbonate concentration of 25 mmol/l. 3. ‘Respiratory’ and ‘metabolic’ acidosis caused little change in pH1 although increases in Pco2 led to relatively greater falls in pH1 than did reduction in external bicarbonate concentration. 4. ‘Respiratory’ and ‘metabolic’ alkalosis caused similar and relatively greater increases in the pH1 when compared with the response to an external acidosis.

Role of ion transfer processes in acid-base regulation with temperature changes in fish

1984 ◽  
Vol 246 (4) ◽  
pp. R441-R451 ◽  
Author(s):  
N. Heisler
Keyword(s):  
Ion Transfer ◽  
Bicarbonate Concentration ◽  
Acid Base ◽  
Fish Tissues ◽  
Model Calculations ◽  
Temperature Changes ◽  
Transfer Processes ◽  
Transfer Mechanisms

The contributions of transmembrane and transepithelial ion transfer processes and of nonbicarbonate buffering to the in vivo acid-base regulation have been evaluated. Model calculations were performed utilizing experimental data on transepithelial transfer of ions relevant for the acid-base regulation, the intracellular buffering properties of fish tissues, and the behavior of intracellular and extracellular pH and bicarbonate concentration with changes of temperature. The results of these studies indicate that the changes in the pK values of physiological nonbicarbonate buffers with changes in temperature support the adjustment of pH to lower values with rising temperature; however, transmembrane and transepithelial ion transfer mechanisms determine the acid-base regulation of intracellular and extracellular compartments.

Acid-Base Effects of Combined Renal Deletion of NBCe1-A and NBCe1-B

2022 ◽  
Author(s):  
Hyun-Wook Lee ◽  
Jill W. Verlander ◽  
Gary E Shull ◽  
Autumn N. Harris ◽  
I. David Weiner
Keyword(s):  
Proximal Tubule ◽  
Splice Variant ◽  
Molecular Mechanisms ◽  
Ammonia Excretion ◽  
Basal Diet ◽  
Acid Base ◽  
Outer Medulla ◽  
Ammonia Metabolism ◽  
Induced Changes ◽  
Acid Loading

The molecular mechanisms regulating ammonia metabolism are fundamental to acid-base homeostasis. Deleting the A splice variant of the Na⁺-bicarbonate cotransporter, electrogenic, isoform 1 (NBCe1-A) partially blocks the effect of acidosis to increase urinary ammonia excretion, and this appears to involve the dysregulated expression of ammoniagenic enzymes in the proximal tubule (PT) in the cortex, but not in the outer medulla (OM). A second NBCe1 splice variant, NBCe1-B, is present throughout the PT, including the OM, where NBCe1-A is not present. The current studies determined the effects of combined renal deletion of NBCe1-A and NBCe1-B on systemic and proximal tubule ammonia metabolism. We generated NBCe1-A/B deletion using Cre-loxP techniques and used Cre-negative mice as controls. Since renal NBCe1-A and NBCe1-B expression is limited to the proximal tubule, Cre-positive mice had proximal tubule NBCe1-A/B deletion (PT-NBCe1-A/B KO). While on basal diet, PT-NBCe1-A/B KO mice had severe metabolic acidosis, yet urinary ammonia excretion was not changed significantly. PT-NBCe1-A/B KO decreased expression of phosphate-dependent glutaminase (PDG) and phospho­enol­pyruvate carboxy­kinase (PEPCK) and increased expression of glutamine synthetase (GS), an ammonia recycling enzyme, in PT in both the cortex and OM. Exogenous acid-loading increased ammonia excretion in control mice, but PT-NBCe1-A/B KO prevented any increase. PT-NBCe1-A/B KO significantly blunted acid loading-induced changes in PDG, PEPCK, and GS expression in the proximal tubule in both the cortex and OM. We conclude that NBCe1-B, at least in the presence of NBCe1-A deletion, contributes to proximal tubule ammonia metabolism in the OM and thereby to systemic acid-base regulation.

Effect of systemic acid-base disorders on ileal intracellular pH and ion transport

1986 ◽  
Vol 250 (5) ◽  
pp. G588-G593 ◽  
Author(s):  
J. D. Wagner ◽  
P. Kurtin ◽  
A. N. Charney
Keyword(s):  
Intracellular Ph ◽  
Respiratory Acidosis ◽  
Strong Correlations ◽  
Sprague Dawley ◽  
Acid Base ◽  
Ileal Mucosa ◽  
Arterial Pco2 ◽  
Co2 Partial Pressure ◽  
Arterial Ph ◽  
Acute Metabolic Acidosis

We previously reported that changes in ileal net Na absorption correlated with arterial pH, changes in net HCO3 secretion correlated with the plasma HCO3 concentration, and changes in net Cl absorption correlated with arterial CO2 partial pressure (PCO2) during the systemic acid-base disorders. To determine whether changes in intracellular pH (pHi) and HCO3 concentration [( HCO3]i) mediated these effects, we measured pHi and calculated [HCO3]i in the distal ileal mucosa of anesthetized, mechanically ventilated Sprague-Dawley rats using 5,5-[14C]dimethyloxazolidine-2,4,-dione and [3H]inulin. Rats were studied during normocapnia, acute respiratory acidosis, and alkalosis, and uncompensated and pH-compensated acute metabolic acidosis and alkalosis. When animals in all groups were considered, mucosal pHi was not altered, but there were strong correlations between mucosal [HCO3]i and both arterial PCO2 (r = 0.97) and [HCO3] (r = 0.61). When we considered the rates of ileal electrolyte transport that characterized these acid-base disorders [A. N. Charney and L.P. Haskell, Am. J. Physiol. 245 (Gastrointest. Liver Physiol. 8): G230-G235, 1983], we found strong correlations between mucosal [HCO3]i and both net Cl absorption (r = 0.88) and net HCO3 secretion (r = 0.82). These findings suggest that the systemic acid-base disorders do not affect ileal mucosal pHi but do alter mucosal [HCO3]i as a consequence of altered arterial PCO2 and [HCO3]. The effects of these disorders on ileal net Cl absorption and HCO3 secretion may be mediated by changes in [HCO3]i. Arterial pH does not appear to alter ileal Na absorption through changes in the mucosal acid-base milieu.

scholarly journals The Boron & De Weer Model of Intracellular pH Regulation

2020 ◽  
Author(s):  
Rossana Occhipinti ◽  
Soroush Safaei ◽  
Peter J. Hunter ◽  
Walter F. Boron
Keyword(s):  
Cell Membrane ◽  
Intracellular Ph ◽  
Ph Regulation ◽  
Quantitative Model ◽  
Historical Background ◽  
Acid Base ◽  
Experimental Conditions ◽  
Subsequent Work ◽  
Energy Dependent ◽  
Parameter Values

The classic Boron & De Weer (1976) paper provided the first evidence of active regulation of pH} in cells by an energy-dependent acid-base transporter. These authors also developed a quantitative model --- comprising passive fluxes of acid-base equivalents across the cell membrane, intracellular reactions, and an active transport mechanism in the cell membrane (modelled as a proton pump) --- to help interpret their measurements of intracellular pH under perturbations of both extracellular CO2/HCO3- and extracellular NH3/NH4+. This Physiome paper seeks to make that model, and the experimental conditions under which it was developed, available in a reproducible and well-documented form, along with a software implementation that makes the model easy to use and understand. We have also taken the opportunity to update some of the units used in the original paper, and to provide a few parameter values that were missing in the original paper. Finally, we provide an historical background to the Boron & De Weer (1976) proposal for active pH regulation and a commentary on subsequent work that has enriched our understanding of this most basic aspect of cellular physiology.

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