Induced pH Changes Research Articles

Osmoregulation in Dunaliella tertiolecta: effects of salt stress, and the external pH on the internal pH

The intracellular pH of the halotolerant green algae Dunaliella tertiolecta, was determined by the distribution of 5,5-dimethyl-2(14C)-oxalolidine-2,5-dione (DMO) between the cell and the surrounding medium. 5,5-dimethyl-2(14C)oxalolidine-2,4-dione was not metabolized by the algal cells. The intracellular pH of Dunaliella tertiolecta was 6.8 in the dark and 7.4 in the light. During a salt stress, after two hours, the intracellular pH was increased by 0.2 pH units in both light and dark. The salt stressed cells maintained a constant pH of about 7.5 over the pH range of 6.5 to 8.5. Because of the relatively low permeability coefficient of the plasma membrane for DMO, this technique does not permit rapid pH determinations during the induction period after a salt stress. The magnitude of the salt induced pH changes measured 2 h after the salt stress implies a minor importance of this alkalization in this time range, but does not exclude a larger importance of pH changes for osmoregulation during the induction period.

代謝性酸・塩基平衡の変化ならびに呼吸性酸・塩基平衡の変化が非脱分極性筋弛緩薬の作用に及ぼす影響に関する研究

代謝性酸・塩基平衡の変化ならびに呼吸性酸・塩基平衡の変化が非脱分極性筋弛緩薬の作用に及ぼす影響に関する研究

Laser-induced pH change in solution

First observations have been made of one-photon and two-photon absorption processes that induce pH changes in various solutions. The concentration of H + or negative ions such as Cl − was measured by selected ion electrodes. The quantum yields for one-photon absorption and two-photon-induced dissociation cross sections were also measured.

Electrooptical studies on proton-binding and -release of bacteriorhodopsin at various pH values

Abstract Electric field induced pH changes of purple membrane suspensions were investigated in the pH range from 4.1 to 7.6 by measuring of the absorbance change of pH indicators. There are, at least, two proton binding sites; one (site 1) releases protons and the other (site 2) takes up protons in the presence of the electric field. The pH dependence of the number of protons released from site 1 and taken up by site 2 indicates that the pK value of site 1 is shifted from 5.0 to 4.6 and that of site 2 from 4.5 to 5.5 by the externally applied electric field of 20 kV/cm. The rate constants of proton binding for site 1 and site 2 in the pH range from 4.7 to 7.3 are estimated to be 2 × 108M−1s−1 and 2 × 107M−1 s−1 respectively.

Pneumoperitoneum induced pH changes in follicular and Douglas fluids during laparoscopic oocyte retrieval in humans.

The effects of different insufflation media gases for pneumoperitoneum on the acidity of follicular fluid and blood acid--base balance were studied in two groups of patients during laparoscopic oocyte retrieval. Insufflation with 100% CO2 was compared with insufflation with 5% CO2 in air. End-tidal CO2 and the acid-base status of arterial blood, follicular and Douglas fluids were evaluated. When using 5% CO2 in air as insufflation gas, pH values and pCO2 levels observed in the aspirated follicular (pH: 7.35 +/- 0.06, pCO2: 38.8 +/- 4.5 mmHg) and Douglas fluid (pH: 7.40 +/- 0.07, pCO2: 38.5 +/- 6.2 mmHg) remained normal. With 100% CO2 insufflation, the follicular fluid pH (7.22 +/- 0.07) and pCO2 (53.1 +/- 10.9 mmHg) and the Douglas fluid pH (6.99 +/- 0.12) and pCO2 (90.3 +/- 18.4 mmHg) were grossly disturbed and outside the physiological range. No differences occurred in pO2 or HCO3 levels. These data suggest that pneumoperitoneum with 5% CO2 in air provides more optimal environmental conditions for oocytes used for in-vitro fertilization. However, further investigations on large patient groups are required to demonstrate whether such environmental conditions influence the success rate of in-vitro fertilization in humans.

Na +/H + exchange and aggregation of human platelets activated by ADP: the exchange is not required for aggregation

Isolated human blood platelets, loaded with the pH-sensitive fluorescence dye 2′,7′-bis(carboxyethyl)-5,6-carboxyfluorescein show cytoplasmic alkalinization upon stimulation with thrombin but acidification with ADP stimulation. In both cases a Na +/H + exchange is activated. This can be revealed by sensitivity of the induced pH changes to amiloride and to 5-N-(3- aminophenyl)amiloride (APA), known inhibitors of the Na +/H + exchanger, and by a dependence on sodium in the external medium. ADP-induced platelet aggregation is not affected by omission of sodium from the external medium. Furthermore, aggregation is barely inhibited (less than 10%) by amiloride or APA at concentrations up to 50 μM while the K i values in affecting the Na +/H + exchange are 5.9 and 1.6 μM for amiloride and APA, respectively. Platelet apparently due to a secondary effect of the agents. It is concluded that platelet aggregation induced by ADP is not dependent on activation of Na +/H + exchange.

Nitrogen source effects on rhizosphere pH and nutrient accumulation by Pacific Northwest conifers

Nitrogen source effects on rhizosphere pH were evaluated for Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco], Sitka spruce [Picea sitchensis (Bong.) Carr.] and western hemlock [Tsuga heterophylla (Raf.) Sarg.] seedlings and a 40-year-old second growth Douglas-fir stand. Nitrogen additions of 400 mg kg−1 decreased rhizosphere pH up to 0.7 units in ammonium treatments and increased pHr by up to 1.2 units in nitrate treatments. Both N sources increased foliar N but did not increase foliar P. Rhizosphere pH effects differed between the two soils used in the seedling study. Ovall soil with higher native ammonium levels had less pH increase with added nitrate. All three conifer seedlings reacted similarly to nitrogen source. Changes in rhizosphere pH of Douglas-fir seedlings were evident one week after nitrogen application and these changes were statistically significant after two weeks. Nitrogen induced pH changes were related to N added but the relation was not linear, and followed the buffering capacity curves of both soils. As pH decreased foliar Mn levels increased dramatically. Rhizosphere pH of a 40-year-old Douglas-fir stand followed the same trends as seedlings. Ammonium decreased pH in the soil surface only, while nitrate increased rhizosphere pH to a depth of 20 to 30 cm. Changes were evident one year after application.

Inhibition of Metabolic Hydrogen Ion Flux Resulting from Cadmium Stress in Aquatic Microecosystems

Periodic changes in pH were monitored at 30 s intervals in naturally-derived, aquatic microeco-systems. The pH of the system was controlled between two setpoints with a microcomputer. When the upper setpoint was reached a light bank was turned off until the pH dropped to the lower setpoint and the light was again turned on. The cycling of the pH in the microcosms was analyzed using time series analysis techniques. Each experiment resulted in a 24 hour control data set and a 24 hour experimental data set that began with the addition of an inhibitor or toxicant. EC50 values (effective concentration for 50% inhibition) of net photosynthesis and respiration of the community were calculated from slopes of the periodic response to cadmium and compared to literature values. The EC50 for dark induced pH change was 3.8 ppm while the EC50 for light induced pH change was 0.51 ppm. Increasing cadmium concentrations caused dominant peaks in the variance periodograms to be shifted to longer periods.

Effects of aluminium and micro-nutrients on the sorption of phosphorus byTrifolium repens L. cv. ‘Grasslands Huia’ from nutrient solutions during plant induced pH changes

The sorption of phosphorus from nutrient solution and the pH change in the nutrient solution were monitored over a 24 hour period forTrifolium repens L. cv. ‘Grasslands Huia’ plants. Two different concentration levels of micro-nutrients (B, Cu, Fe, Mn and Zn) and Al formed the factors of a fractional replicate of a 26 factorial design.

Solar energy conversion and storage through synthetic light-driven proton pumps

Two approaches to the conversion and storage of solar energy through synthetic light-driven proton pumps are discussed and experimental data on model systems are presented. The more promising of these is photoelectrodialytic acid-base production from salt in the charge half cycle and reversible recombination of acid and base to yield electric power in the discharge half cycle. The second method continues previous studies on photochemically induced pH changes in thionine-metal ion systems with improved, though not yet practical, results.

Respiratory properties of blood of the gray seal,Halichoerus grypus

1. This study examined the O2 and CO2 transport and acid-base properties of blood of the gray seal. Phocid seals use theblood as an oxygen store for aerobic metabolism during diving. Particular objectives were to determine whether CO2 exerts a specific effect on blood oxygen affinity, and whether the Bohr coefficient varies between different levels of oxygen saturation. 2. Hematocrit (0.50), blood hemoglobin concentration (12.8 mM heme) and cell hemoglobin concentration (25.4 mM) were, high compared to terrestrial mammals but similar to other seals (Table 2). Isoelectric focusing resolved the same four hemoglobin components in six individuals, with the most important components constituting 60% and 20% of the total. Oxygen affinity (P50=27.1 Torr at pH 7.4, 37.5°C) and equilibrium curve shape (nH=2.59) were similar to other phocid seals and terrestrial mammals (Tables 1,4). The Bohr coefficient for CO2 induced pH change (−0.51) was only slightly higher than that for fixed acid incuded pH change (−0.47), implying little oxygen-linked carbamino formation (Table 1). The bohr coefficients were at the upper end of the range found in terrestrial mammals, and did not vary with oxygen saturation (Table 1). 3. Blood buffer value was high (31.5 mM/pH), in accord with the high hemoglobin concentration (Table 3). The Haldane effect (−0.32 mol CO2 per mol O2, Fig. 2) was similar to those in blood of other seals and dog, but higher than that in human blood. Hydrogen ion uptake by hemoglobin upon deoxygenation (0.40 mol/mol O2) was greater than in human blood, in proportion to the larger fixed acid Bohr coefficient in the seal. 4. Blood of the gray seal, like that of other phocid seals, is distinguished from that of terrestrial mammals primarily by high hemoglobin concentration and oxygen capacity, which increase blood oxygen stores available for use during diving. Other properties are similar to those of terrestrial mammals or differ only as a consequence of the high hemoglobin concentration.

Acid base changes during recovery from disturbance and during long term hypoxic exposure in the lobster Homarus vulgaris

AbstractHemolymph O2 and CO2 levels and pH were measured in lobsters (H. vulgaris) as they settled in normoxic conditions and during prolonged exposure to moderately hypoxic seawater. Initial handling and transfer to the experimental conditions resulted in a marked acidosis. Complete recovery took from 24 to 48 hours. Samples of hemolymph taken after 48 hours yielded “settled” normoxic levels for O2 CO2 and pH. Subsequent exposure to moderately hypoxic water caused an initial respiratory alkalosis associated with pronounced hyperventilation. The induced pH change was sufficient to cause a marked increase in the oxygen affinity of the hemocyanin, allowing almost complete saturation of post‐branchial (arterial) hemolymph despite a 3‐fold decrease in hemolymph oxygen tension. Prolonged exposure to hypoxia resulted in an attenuation of the hyperventilation response but hemolymph bicarbonate levels rose substantially and may have maintained pH high and thus kept oxygen affinity above the normoxic level. On return to normoxic water both ventilation volume and hemolymph carbon dioxide decreased and pH and oxygen affinity returned to normoxic levels.

Spectrophotometric measurements of metabolically induced pH changes in frog skeletal muscle

A means of measuring pH spectrophotometrically with two pH-sensitive indicators, neutral red (NR) and bromcresol purple (BCP), is presented. Theoretical calculations and experimental measurements of pH in solution correspond in a satisfactory manner for both dyes. Spectrophotometric determinations of pH were made of dye-equilibrated frog sartorius muscles. A more accurate indication of shifting intracellular pH (pH i) was obtained with NR than with BCP, since only the spectra of NR-equilibrated muscles were insensitive to changes in external pH over the range 7.0–6.0. Muscles were stimulated in oxygenated Ringer's and the latent phase of acidification correlated with lactic acid production by analysis of tissue frozen after spectral determination of ΔpH i. Buffering capacities were calculated to be 0.041 to 0.048 g equiv per liter of strong acid or base per resultant ΔpH for a pH i range covering 0.25 unit.

Differential Tolerances of Triticale, Wheat, Rye, and Barley to Aluminum in Nutrient Solution1

AbstractAluminum toxicity to cereals is an important consideration when adapting a new crop to the acid soils of the Southeast. The objective of this study was to evaluate the relative tolerances of different cultivars of triticale (X Triticosecale) a new crop, wheat (Triticum aestivum L.), rye (Secale cereale L.), and barley (Hordeum vulgare L.) to Al in nutrient solution with a pH of 4.8 at the time of transplanting. Plant induced pH change in the nutrient solution and dry matter produced were used as criteria for evaluating Al tolerance. Triticale resembled the other three species in increasing the pH of the solution during growth when no Al was added to the nutrient solution. When 6 ppm Al was added, triticale ‘6TA 131’ and ‘6TA 298,’ Al‐tolerant ‘Thorne’ and ‘Seneca’ wheats, and ‘Vitagraze’ rye increased the nutrient solution pH to values higher than 5.0. However, triticales ‘6TA 385,’ ‘6TA 203,’ and 6TA 522,’ the different barley cultivars, and ‘Abruzzi’ rye either decreased or had no effect on solution pH. ‘Atlas 66’ wheat induced significantly higher pH at 6 ppm Al added to the medium than all the other cultivars tested.The addition of 6 ppm Al to the nutrient solution reduced the shoot growth of the different cultivars generally in a similar manner. However, reductions in root dry matter by Al indicated that, on the average, Al tolerances were: Al‐tolerant wheat and rye > triticale and Al‐tolerant barley > Al‐sensitive barley and Al‐sensitive wheat. The pH changes induced by the plants in the solution with 6 ppm Al generally confirmed the same order of tolerance as obtained from reductions in root dry matter. Increasing Al in solution significantly increased Al but decreased Ca and P in triticale, wheat, and rye. Aluminum‐sensitive wheat contained higher Al in roots than Al‐tolerant wheat. The roots of triticale and rye cultivars significantly differed in Al concentration.

Assessment of denture plaque pH in subjects with and without denture stomatitis.

To evaluate the "resting" pH and induced pH changes in denture plaque, soft deposits were collected from the fitting surface of the denture, pooled and suspended in water. Plaque pH was determined with microelectrode equipment before and after mouth rinsing with a sucrose solution. A characteristic level in the "resting" pH of denture plaque was found in most of 12 subjects tested. pH values below the baseline level were recorded for more than 2 h after a rinse. The pH depressions were more pronounced in maxillary than in mandibular plaque. Further, the pH minima tended to be lower in subjects with denture stomatitis than in controls. No clear relationship could be established between the "resting" pH and the concentration of Candida hyphae in denture smears or palatal inflammation.

Venous stasis and fibrinolytic activity. Influence of graduated compression and changes in gas values.

The influence of graduated venous compression of legs on changes in gas values, pH and fibrinolytic activity was investigated, and the correlation between changes in arms and legs of euglobulin clot lysis time (ELT) and of oxygen tension (pO2), oxygen saturation (O2%), carbon dioxide tension (pCO2), pH, and haematocrit was evaluated. The cuff pressure on arms was midway between systolic and diastolic pressure (mean blood pressure), and in 16 cases the same inflation pressure was used for compression of the legs (group I). In another 16 cases (group II) the very mean blood pressure of the leg was used on the legs, in general exceeding the mean pressure of the arm by approximately 35 mm Hg. The employed graduation of the venous compression did not affect changes in the measured parameters. In spite of significantly different cuff pressure, the changes in group I and group II were identical, and the usual significant differences between arm and leg in changes of O2%, haematocrit, ELT, and fibrinogen values were found in both groups.No correlation between induced activator activity and changes in pO2, O2 %, pCO2, pH and haematocrit could be demonstrated.

The Interaction of pH and Aeration in CI Uptake by Barley Roots

AbstractThe uptake of Cl by excised roots of barley (Hordeum vulgare L.) from KC1 solution maintained at high pH was markedly reduced by high rates of aeration, whereas K uptake was scarcely affected. Aeration rate had relatively minor effects at low pH. The effect of high aeration rate at pH 9 could be overcome by the use of buffered solutions. In unbuffered solutions the H resulting from the excess cation uptake together with that produced from respiratory CO2 was sufficient to materially reduce the pH of the solution. The reduction in pH favored the uptake of Cl which is adversely affected by high pH. The effect of aeration rate could be explained in terms of root induced pH changes and film diffusion involving the solution film adjacent to the root surface.

Mechanism of Calcium and Adenosine Triphosphate Induced pH Changes in Sarcotubular Membrane Fractions from Rabbit Skeletal Muscle

AbstractAddition of calcium to a suspension of sarcotuhular membrane fragments in the presence of MgCl2 and ATP caused a drop in pH followed by a rise. The pH cycle could be obtained several times by sequential additions of calcium. Addition of Triton X—100 caused similar pH changes, which were substantially slower in the absence of magnesium. During the pH drop phase an increased rate of inorganic phosphate liberation was observed, during the pH rise phase production of ammonia was demonstrated. The pH events are explained by the combined action of three enzyme activities —ATP phosphohydrolase (E.C. 3.6.1.3), ATP:AMP phosphotransferase (E.C. 2.7.4.3) and AMP aminohydrolase (E.C. 3.5.4.6). The highest specific activity of AMP aminohydrolase was found in the sarcotubular membrane and ‘light’ membrane fractions. Accumulation of calcium in conditions where binding by mitochondria was excluded, was used as a biochemical marker for sarcotubular membranes. These findings are discussed in relation to pH changes observed in muscular activity and as a mechanism of preventing excessive drops in muscular intracellular pH.