Disease relevance of Hydrogen-Ion Concentration

• Dichloroacetate treatment of patients with severe lactic acidosis results in statistically significant but clinically unimportant changes in arterial-blood lactate concentrations and pH and fails to alter either hemodynamics or survival [1].
• Moreover, because chronic hyperventilation paradoxically lowers blood pH still further in dogs with metabolic acidosis, we desired to study the effect of chronic hypocapnia on the plasma bicarbonate concentration (and blood pH) in normal human subjects in whom acidosis had been induced with ammonium chloride [2].
• Low pH induces swiveling of the glycoprotein heterodimers in the Semliki Forest virus spike complex [3].
• The function of the N-methyl-D-aspartate (NMDA)-preferring glutamate receptor can be regulated by extracellular pH, a process that may be important during ischemia in the brain or during seizures [4].
• Purified human IL-1, pH 7.0, and recombinant-generated murine IL-1, pH 5.0, increased the expression of factor B and other positive acute-phase proteins in human hepatoma cells but decreased the expression of albumin, a negative acute-phase reactant [5].

Psychiatry related information on Hydrogen-Ion Concentration

• These effects of lithium were not associated with changes in animal behavior, nor were there any significant differences in blood levels of calcium, phosphorus, alkaline phosphatase, creatinine, pH, or parathyroid hormone [6].
• Panic attacks were not associated with changes in epinephrine or calcium levels or pH [7].
• A short reaction time and neutral pH values can be used in the presence of the two reagents, ensuring the integrity of both of the proteins and the iron-sulfur cluster of the ferredoxin [8].
• Basolateral secretion of amyloid precursor protein in Madin-Darby canine kidney cells is disturbed by alterations of intracellular pH and by introducing a mutation associated with familial Alzheimer's disease [9].
• 2. During perfusion with modified Krebs solution (26 mM HCO3-, 5 % CO2, pH 7.4), there was no consistent activity in IIM, though rhythmic inspiratory motor activity always appeared in the C4 ventral root [10].

High impact information on Hydrogen-Ion Concentration

• The binding of two protons by the quinone is associated with the transfer of the second electron to QB at a rate of ca. 10(3) s-1 (pH 7) [11].
• Extracellular pH shifts can occur within milliseconds of neural activity, arise from an assortment of mechanisms, and are governed by the activity of extracellular carbonic anhydrase [12].
• The activity of the network depends on CO2 and pH levels, via cholinergic relays, as well as being modulated at both the RVLM and motoneuronal levels by endogenous serotonin, substance P, and catecholamine mechanisms [13].
• Thus the lactate-proton transporter is of functional importance for pH regulation in association with muscle activity [14].
• This collapse of the surface pH gradients may reflect, at least in part, that such studies have been mostly performed on non-acid-secreting mucosa where the supply of HCO3- to the interstitium from the parietal cells will be reduced [15].

Chemical compound and disease context of Hydrogen-Ion Concentration

• Nitrogen bomb cavitates of DIFP-treated PMN were centrifuged through discontinuous Percoll gradients, each fraction extracted with 0.05 M glycine, pH 2.0, and tested for the killing of Escherichia coli. greater than 90% of BF coisolated with the azurophil granules [16].
• Direct glucose-induced Na+/H+ antiport activation was confirmed by measuring Na(+)-dependent intracellular pH recovery from intracellular acidosis [17].
• Changes in arterial pH and bicarbonate, or in the concentrations of Na+, K+, urea, or creatinine in plasma or cerebrospinal fluid were similar in uremic animals with intact parthyroid glands and in previously parathyroidectomized uremia dogs [18].
• We have tested the hypothesis that severe lypoxia causes apnea, regardless of the arterial CO2 and pH, and that extreme hypoxia causes gasping [19].
• When compared with normocapneic rats with similar FLHCO3, no stimulation of EP or overall proximal HCO3 reabsorption was found with either acute hypercapnia (PaCO2 = 74 mmHg, pH = 7.23) or chronic hypercapnia (PaCO2 = 84 mmHg, pH = 7.31) [20].

Biological context of Hydrogen-Ion Concentration

• During intense muscle activity and in the recovery period, the lactate and H+ effluxes are mainly mediated by the lactate-proton transporter, which reduces the accumulation of lactate in muscle as well as the drop in internal pH suggested to be involved in muscle fatigue [14].
• Our data, together with the known requirement for active proton secretion to maintain proper endolymph pH, implicate ATP6B1 in endolymph pH homeostasis and in normal auditory function [21].
• In seven normal subjects given ammonium chloride for three days, the anion gap was negative (-27 +/- 9.8 mmol per liter) and the urinary pH under 5.3 (4.9 +/- 0.03) [22].
• As opposed to chloroquine and alkaline incubation conditions (pH 8.0), the amines reduced the maximal rate of endocytosis considerably, indicating a reduction in number of available receptors [23].
• Salt bridges that stabilize the positioning of the N-terminal proenzyme segment across the active site of pepsin are disrupted at low pH, releasing the amino-terminal segment and thereby exposing the catalytic apparatus and the substrate-binding sites [24].

Anatomical context of Hydrogen-Ion Concentration

• The pH in Atp6i-/- liver lysosomes and proton transport in microsomes of Atp6i-/- kidney are identical to that in wild-type mice [25].
• Therefore, the trans cisternae of the Golgi apparatus and forming secretory vesicles have an acidic pH [26].
• Using image intensified fluorescence microscopy and digital image analysis, we determined that the F-Tf containing structure has a pH of 6.4 +/- 0.2, while endocytic vesicles containing F-alpha 2M have a pH of 5.4 +/- 0 [27].
• Estrogen replacement restores atrophic mucosa, lowers vaginal pH, and may prevent urinary tract infections [28].
• RecA binds to linear duplex fd DNA in solutions of 0.01 M Tris (pH 7.5) to yield chains of beads which, in the presence of Mg2+ and ATP, coalesce into smooth filaments with a length of 1.9 micrometers (the length of protein-free fd duplex DNA) and have a fiber diameter of 12 nm [29].

Associations of Hydrogen-Ion Concentration with chemical compounds

• In the stomach, where luminal acidity can fall to around pH 1, other mechanisms of protection must exist, since the surface pH gradient is reported to collapse when luminal H+ exceeds approximately 10 mM [15].
• These effects of catecholamines were independent of the venous pH, the plasma bicarbonate and serum glucose levels, and urinary potassium excretion, and they did not appear to be due to insulin [30].
• Urinary pH decreased below 5.3 after ammonium chloride administration in all 15 normal controls, but in only 13 of 18 patients [31].
• However, protein denaturants (4 M urea or alkaline pH) extracted the 70-mer from the membrane [32].
• The observed pH dependent protection of N-7 of dG residues within the insert suggests that these residues are either Hoogsteen or reverse Hoogsteen base-paired to protonated dC residues of the polypyrimidine strand [33].

Gene context of Hydrogen-Ion Concentration

• We also show that the artificial acidic activator AH has structural properties that are markedly different from the natural GAL4 and GCN4 domains and does not adopt a beta-rich structure at reduced pH [34].
• To identify proteins that bind mammalian IAP homolog A (MIHA, also known as XIAP), we used coimmuno-precipitation and 2D immobilized pH gradient/SDS PAGE, followed by electrospray ionization tandem mass spectrometry [35].
• We also demonstrate that soluble TfR and HFE bind tightly at the basic pH of the cell surface, but not at the acidic pH of intracellular vesicles [36].
• Vanilloid receptor-1 (VR1, also known as TRPV1) is a thermosensitive, nonselective cation channel that is expressed by capsaicin-sensitive sensory afferents and is activated by noxious heat, acidic pH and the alkaloid irritant capsaicin [37].
• P2X2 receptors are unique among homomeric forms in their potentiation by low pH [38].

Analytical, diagnostic and therapeutic context of Hydrogen-Ion Concentration

• We studied the rate of nosocomial pneumonia among 130 patients given mechanical ventilation in an intensive care unit who were receiving as prophylaxis for stress ulcer either sucralfate (n = 61), which does not raise gastric pH, or conventional treatment with antacids, histamine type 2 (H2) blockers, or both (n = 69) [39].
• After initial gel filtration and separation by chromatofocusing IL-1/5 was purified by chromatography on hydroxyapatite and the ion exchangers, Mono S and Mono Q; IL-1/8 was purified by chromatography at pH 4.0 and pH 6.4 on Mono S [40].
• This result was further substantiated in experiments where biotin-peptide/class II complexes were extensively dialyzed at low pH followed by analysis on Western blots probed with avidin [41].
• Using surface plasmon resonance, we show that at neutral pH, mouse CD1 and human CD1d bind to immobilized alpha-GalCer, unlike human CD1b, which requires acidic pH for lipid antigen binding [42].
• When isoelectric focusing electrophoresis was carried out over a narrow range of pH (5-7), each of the apolipoprotein E isoforms of affected members was observed as a doublet, even after reduction of dimers of the protein with 2-mercaptoethanol and treatment with neuraminidase to minimize the content of sialylated forms of the protein [43].

References