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The American Journal of Physiology Aug 1993Intracellular pH recovery from an acute alkaline load in rat hepatocytes is mediated by a Cl(-)-HCO3- exchanger, which is electroneutral, Na+ independent, and...
Intracellular pH recovery from an acute alkaline load in rat hepatocytes is mediated by a Cl(-)-HCO3- exchanger, which is electroneutral, Na+ independent, and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) sensitive. Stimulation of this Cl(-)-HCO3- exchanger requires intact microtubules, suggesting that vesicular transport may be required to activate this exchanger. To determine if intracellular alkalinization stimulates biliary HCO3- excretion and bile flow in the intact liver by vesicle-mediated exocytosis, isolated perfused rat livers (IPRL) were alkalinized by two protocols. Isohydric changes in CO2 and HCO3- concentrations induced transient increases in bile flow by 36% (P < 0.01), which were abolished by DIDS (0.01 mM), inhibited by pretreatment with colchicine (P = 0.01), but not affected by membrane depolarization with the K(+)-channel blocker BaCl2 (1 mM). Similarly, perfusion with 20 mM NH4Cl produced a 42% increase in bile flow (P < 0.01) and a 26% increase in biliary HCO3- excretion. Both the increases in bile flow and HCO3- excretion were almost completely blocked by DIDS and inhibited by pretreatment with colchicine (P < 0.01). Biliary excretion of horseradish peroxidase was also increased during intracellular alkalinization with either protocol (P < 0.01). These findings suggest that intracellular alkalinization stimulates bile flow and biliary HCO3- excretion. Microtubule-dependent vesicular-mediated exocytosis is involved in this response.
Topics: 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; Alkalies; Animals; Anions; Barium; Bicarbonates; Bile; Biological Transport; Colchicine; Exocytosis; Horseradish Peroxidase; Hydrogen-Ion Concentration; In Vitro Techniques; Intracellular Membranes; Liver; Male; Potassium Channels; Rats; Rats, Sprague-Dawley
PubMed: 8368316
DOI: 10.1152/ajpgi.1993.265.2.G347 -
The Journal of Antimicrobial... Oct 1983Clindamycin is concentrated within human neutrophils and their lysosomes because the intralysosomal pH is highly acidic and this antibiotic behaves as a weak base. We...
Clindamycin is concentrated within human neutrophils and their lysosomes because the intralysosomal pH is highly acidic and this antibiotic behaves as a weak base. We have examined the ability of clindamycin to buffer (alkalinize) the intralysosomal pH and studied the consequences of alterations of lysosomal pH on neutrophil functions. At therapeutic concentrations of clindamycin (0.01 mM), we observed no effect on intralysosomal pH as monitored by the distribution and fluorescence of a weakly basic fluorescent probe 9-aminoacridine. However, at higher concentrations (1.0 mM), clindamycin alkalinized the intralysosomal pH and inhibited neutrophil lysosomal degranulation to several stimuli, and superoxide production in response to phorbol myristate acetate. Neutrophil locomotion was unaffected even at concentrations of clindamycin which increased the intralysosomal pH. We conclude that clindamycin accumulates in acidic neutrophil lysosomes and, at high concentrations, alkalinizes the intralysosomal pH. Coincident with lysosomal alkalinization there is inhibition of secretion and respiratory burst activity suggesting that intact lysosomal pH regulation is important for these functions. Clindamycin provides a useful tool to examine the relationships between weak base uptake, lysosomal pH and neutrophil functions.
Topics: Adult; Cell Movement; Chemotaxis, Leukocyte; Clindamycin; Cytoplasmic Granules; Humans; Hydrogen-Ion Concentration; In Vitro Techniques; Lysosomes; Neutrophils; Superoxides
PubMed: 6315671
DOI: 10.1093/jac/12.suppl_c.39 -
Journal of the American Chemical Society Feb 2012A strategy of reaction-environment modulation was employed to change the surface property of a semiconductor photocatalyst to enhance its photocatalytic performance....
A strategy of reaction-environment modulation was employed to change the surface property of a semiconductor photocatalyst to enhance its photocatalytic performance. Surface alkalinization induced by a high alkalinity of the solution environment significantly shifted the surface energy band of a SrTiO(3) photocatalyst to a more negative level, supplying a strong potential for H(2)O reduction and consequently promoting the photocatalytic efficiency of H(2) evolution. This mechanism is also applicable for visible-light-sensitive La,Cr-codoped SrTiO(3) photocatalyst, which hence, could achieve a high apparent quantum efficiency of 25.6% for H(2) evolution in CH(3)OH aqueous solution containing 5 M NaOH at an incident wavelength of 425 ± 12 nm.
Topics: Alkalies; Catalysis; Hydrogen; Oxides; Particle Size; Photochemical Processes; Strontium; Surface Properties; Titanium
PubMed: 22280023
DOI: 10.1021/ja210610h -
Biochimica Et Biophysica Acta Nov 2013Mechanical wounding of cell walls occurring in plants under the impact of pathogens or herbivores can be mimicked by cell wall incision with a glass micropipette....
Mechanical wounding of cell walls occurring in plants under the impact of pathogens or herbivores can be mimicked by cell wall incision with a glass micropipette. Measurements of pH at the surface of Chara corallina internodes following microperforation of cell wall revealed a rapid (10-30s) localized alkalinization of the apoplast after a lag period of 10-20s. The pH increase induced by incision could be as large as 3 pH units and relaxed slowly, with a halftime up to 20min. The axial pH profile around the incision zone was bell-shaped and localized to a small area, extending over a distance of about 100μm. The pH response was suppressed by lowering cell turgor upon the replacement of artificial pond water (APW) with APW containing 50mM sorbitol. Stretching of the plasma membrane during its impression into the cell wall defect is likely to activate the Ca(2+) channels, as evidenced from sensitivity of the incision-induced alkalinization to the external calcium concentration and to the addition of Ca(2+)-channel blockers, such as La(3+), Gd(3+), and Zn(2+). The maximal pH values attained at the incision site (~10.0) were close to pH in light-dependent alkaline zones of Chara cells. The involvement of cytoskeleton in the origin of alkaline patch was documented by observations that the incision-induced pH transients were suppressed by the inhibitors of microtubules (oryzalin and taxol) and, to a lesser extent, by the actin inhibitor (cytochalasin B). The results indicate that the localized increase in apoplastic pH is an early event in mechanoperception and depends on light, cytoskeleton, and intracellular calcium.
Topics: Alkalies; Calcium; Cell Wall; Chara; Chlorophyll; Fluorescence; Hydrogen-Ion Concentration; Ion Transport; Mechanotransduction, Cellular; Photosynthesis
PubMed: 23850637
DOI: 10.1016/j.bbamem.2013.07.002 -
Astrobiology Feb 2016Over the last 70 years, prebiotic chemists have been very successful in synthesizing the molecules of life, from amino acids to nucleotides. Yet there is strikingly... (Review)
Review
Over the last 70 years, prebiotic chemists have been very successful in synthesizing the molecules of life, from amino acids to nucleotides. Yet there is strikingly little resemblance between much of this chemistry and the metabolic pathways of cells, in terms of substrates, catalysts, and synthetic pathways. In contrast, alkaline hydrothermal vents offer conditions similar to those harnessed by modern autotrophs, but there has been limited experimental evidence that such conditions could drive prebiotic chemistry. In the Hadean, in the absence of oxygen, alkaline vents are proposed to have acted as electrochemical flow reactors, in which alkaline fluids saturated in H2 mixed with relatively acidic ocean waters rich in CO2, through a labyrinth of interconnected micropores with thin inorganic walls containing catalytic Fe(Ni)S minerals. The difference in pH across these thin barriers produced natural proton gradients with equivalent magnitude and polarity to the proton-motive force required for carbon fixation in extant bacteria and archaea. How such gradients could have powered carbon reduction or energy flux before the advent of organic protocells with genes and proteins is unknown. Work over the last decade suggests several possible hypotheses that are currently being tested in laboratory experiments, field observations, and phylogenetic reconstructions of ancestral metabolism. We analyze the perplexing differences in carbon and energy metabolism in methanogenic archaea and acetogenic bacteria to propose a possible ancestral mechanism of CO2 reduction in alkaline hydrothermal vents. Based on this mechanism, we show that the evolution of active ion pumping could have driven the deep divergence of bacteria and archaea.
Topics: Acetyl Coenzyme A; Alkalies; Carbon Cycle; Hydrothermal Vents; Models, Theoretical; Origin of Life
PubMed: 26841066
DOI: 10.1089/ast.2015.1406 -
American Journal of Kidney Diseases :... Feb 2020Alkali therapy for certain organic acidoses remains a topic of ongoing controversy, but little attention has been given to a related medical controversy, namely the... (Review)
Review
Alkali therapy for certain organic acidoses remains a topic of ongoing controversy, but little attention has been given to a related medical controversy, namely the prescription of alkali for respiratory acidosis. We first describe the determinants of carbon dioxide retention in the 2 types of respiratory failure; hypercapnic respiratory failure and hypoxemic respiratory failure with coexisting hypercapnia. We then highlight the deleterious consequences of severe acidemia for several organ systems, particularly the cardiovascular and central nervous systems. We argue that alkali therapy is not indicated for respiratory acidosis as a simple acid-base disturbance. Notwithstanding, we recommend prescription of alkali for severe acidemia caused by mixed acidosis (ie, combined respiratory and metabolic acidosis) or permissive hypercapnia. We examine the utility of alkali therapy in various clinical scenarios incorporating respiratory acidosis. We conclude that controlled studies will be required to test the impact of alkali therapy on clinical outcomes of these clinical settings. Such studies should also examine the optimal mode of administering alkali (amount, rate, and tonicity) and the blood pH to be targeted. The development of new buffers should be explored, especially systems that do not generate carbon dioxide or even consume it.
Topics: Acid-Base Equilibrium; Acidosis, Respiratory; Alkalies; Carbon Dioxide; Humans; Treatment Outcome
PubMed: 31473018
DOI: 10.1053/j.ajkd.2019.05.029 -
Plant Science : An International... Jun 2022The mechanisms by which plants respond to alkali salt stress are still obscure, and the relevance of alkaline pH under combined alkali salt stress. Early stress...
Alkali salt stress causes fast leaf apoplastic alkalinization together with shifts in ion and metabolite composition and transcription of key genes during the early adaptive response of Vicia faba L.
The mechanisms by which plants respond to alkali salt stress are still obscure, and the relevance of alkaline pH under combined alkali salt stress. Early stress responses can indicate mechanisms leading to damage and plant resistance. The apoplast contains essential determinants for plant growth, specifically early apoplastic pH fluctuations are induced by many stressors and hypothesized to be involved in stress signalling. Hence, this study aims to identify fast responses specific to alkaline pH and alkali salt stress by exposing the root of hydroponically grown Vicia faba L. plants to 150 min of either 50 mM NaHCO (pH 9) treatment or alkaline pH 9 alone. Apoplastic pH was monitored in real-time by ratiometric fluorescence microscopy simultaneously with SWIR transmission-based measurements of leaf water content (LWC). Moreover, we examined the effect of these stresses on apoplastic, symplastic and xylem ion and metabolite composition together with transcriptions of certain stress-responsive genes. Physiological and transcriptional changes were observed in response to NaHCO but not to alkaline pH alone. NaHCO elicited a transient reduction in LWC, followed by a transient alkalinization of the apoplast and stomatal closure. Simultaneously, organic acids and sugars accumulated. Fast upregulation of stress-responsive genes showed the significance of gene regulation for early plant adaptation to alkali salt stress.
Topics: Alkalies; Hydrogen-Ion Concentration; Plant Leaves; Plant Roots; Salt Stress; Vicia faba; Water
PubMed: 35487662
DOI: 10.1016/j.plantsci.2022.111253 -
Advances in Chronic Kidney Disease Jan 2009The aim of this article was to review the most widely researched adjuvant medical therapies for the surgical management of urolithiasis. Articles were identified and... (Review)
Review
The aim of this article was to review the most widely researched adjuvant medical therapies for the surgical management of urolithiasis. Articles were identified and reviewed from PubMed and Medline databases with MeSH headings focusing on the various surgical treatments of urolithiasis and adjuvant therapy. Additional articles were retrieved from references and conference proceedings. Surgical treatments reviewed included shockwave lithotripsy, ureteroscopy, and percutaneous nephrolithotomy. Adjuvant therapy was considered medical or complementary therapy as an adjunct to these surgical interventions. Adjuvant therapy for the surgical management of urolithiasis has been documented to increase stone-free rates, reduce stone remission rates, prevent renal damage, and decrease postoperative morbidity. A variety of agents have been studied, ranging from antioxidants to alpha-blockers and to alkalinizing agents. Additionally, there is increasing interest in complementary adjuvant therapy (ie, acupuncture). Adjuvant therapy is a fertile area for research in the surgical management of urolithiasis. The optimal agents have yet to be determined and therefore further investigation is warranted and necessary.
Topics: Adrenergic alpha-Antagonists; Alkalies; Antioxidants; Combined Modality Therapy; Humans; Lithotripsy; Nephrolithiasis; Nephrostomy, Percutaneous; Secondary Prevention
PubMed: 19095206
DOI: 10.1053/j.ackd.2008.10.007 -
The Journal of Family Practice Dec 1995People working with cement should be aware of the potential for cement burn. The alkalinity of cement is due to the exothermic reaction of calcium oxide with water,...
People working with cement should be aware of the potential for cement burn. The alkalinity of cement is due to the exothermic reaction of calcium oxide with water, which forms calcium hydroxide. Prolonged exposure of the skin to wet cement may result in a caustic burn.
Topics: Adult; Alkalies; Burns; Caustics; Humans; Male; Middle Aged; Necrosis; Pseudomonas aeruginosa; Severity of Illness Index; Skin; Skin Diseases
PubMed: 7500071
DOI: No ID Found -
Colorado Medicine Dec 1982
Topics: Alkalies; Child, Preschool; Digestive System; Digestive System Diseases; Foreign Bodies; Humans; Infant; Male; Metals; Necrosis
PubMed: 7151364
DOI: No ID Found