scholarly journals Regulatory effect of external pH on the intracellular pH in alkalophilic cyanobacteria Microcystis aeruginosa and Hapalosiphon welwltschii.

1994 ◽  
Vol 40 (3) ◽  
pp. 261-263 ◽  
Author(s):  
ALKA DWIVEDI ◽  
USHA K. SRINIVAS ◽  
HRIDAY NARAIN SINGH ◽  
HAR DARSHAN KUMAR
Keyword(s):  
Intracellular Ph ◽  
Microcystis Aeruginosa ◽  
Regulatory Effect ◽  
External Ph

scholarly journals Intracellular pH Distribution in Saccharomyces cerevisiae Cell Populations, Analyzed by Flow Cytometry

2005 ◽  
Vol 71 (3) ◽  
pp. 1515-1521 ◽  
Author(s):  
Minoska Valli ◽  
Michael Sauer ◽  
Paola Branduardi ◽  
Nicole Borth ◽  
Danilo Porro ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Flow Cytometry ◽  
Intracellular Ph ◽  
Environmental Changes ◽  
Physiological State ◽  
Yeast Cells ◽  
Cell Populations ◽  
Ph Homeostasis ◽  
Ph Distribution ◽  
External Ph

ABSTRACT Intracellular pH has an important role in the maintenance of the normal functions of yeast cells. The ability of the cell to maintain this pH homeostasis also in response to environmental changes has gained more and more interest in both basic and applied research. In this study we describe a protocol which allows the rapid determination of the intracellular pH of Saccharomyces cerevisiae cells. The method is based on flow cytometry and employs the pH-dependent fluorescent probe carboxy SNARF-4F. The protocol attempts to minimize the perturbation of the system under study, thus leading to accurate information about the physiological state of the single cell. Moreover, statistical analysis performed on major factors that may influence the final determination supported the validity of the optimized protocol. The protocol was used to investigate the effect of external pH on S. cerevisiae cells incubated in buffer. The results obtained showed that stationary cells are better able than exponentially grown cells to maintain their intracellular pH homeostasis independently of external pH changes. Furthermore, analysis of the intracellular pH distribution within the cell populations highlighted the presence of subpopulations characterized by different intracellular pH values. Notably, a different behavior was observed for exponentially grown and stationary cells in terms of the appearance and development of these subpopulations as a response to a changing external pH.

Effects of extracellular pH, PCO2, and HCO3- on intracellular pH in isolated rat taste buds

1997 ◽  
Vol 273 (3) ◽  
pp. C1008-C1019 ◽  
Author(s):  
V. Lyall ◽  
G. M. Feldman ◽  
G. L. Heck ◽  
J. A. DeSimone
Keyword(s):  
Steady State ◽  
Intracellular Ph ◽  
Imaging Techniques ◽  
Taste Receptor ◽  
Taste Bud ◽  
Apical Process ◽  
Ethanesulfonic Acid ◽  
Induced Changes ◽  
The Relationship ◽  
External Ph

We studied the effects of changing external pH (pHo), external bicarbonate concentration ([HCO3-]o), and PCO2 on taste receptor cell (TRC) intracellular pH (pHi) in taste bud fragments (TBFs) isolated from rat circumvallate and fungiform papillae with the pH-sensitive fluoroprobe 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF) using microfluorometric and imaging techniques. In N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid-buffered solutions, TRC pHi responded rapidly and monotonically to changes in pHo between 6.5 and 8.0. The relationship between pHi and pHo was steep, with slopes varying between 0.8 and 1.2. Similarly, varying pHo by changing PCO2 at constant [HCO3-]o or changing [HCO3-]o at constant PCO2 led to rapid, monotonic changes in pHi. The relationship between pHi and pHo was once again steep, with slopes varying between 0.8 and 1.2. However, simultaneous changes in PCO2 and [HCO3-]o at constant pHo did not cause any significant changes in steady-state pHi. In imaging studies, single, isolated TRCs responded to changes in pHo, with parallel changes in pHi in the soma and apical process. In addition, changes in pHo induced parallel changes in pHi throughout TBFs. These data suggest that the steady-state TRC pHi is a function of pHo. Changes in TRC pHi may be involved in acid sensing, and salivary [HCO3-] may play a role in the maintainance of steady-state TRC pHi and in the neutralization of acid-induced changes in pHi.

The pH dependence of the contractile response of fatigued skeletal muscle

1987 ◽  
Vol 65 (4) ◽  
pp. 648-658 ◽  
Author(s):  
G. W. Mainwood ◽  
J. M. Renaud ◽  
M. J. Mason
Keyword(s):  
Action Potential ◽  
Intracellular Ph ◽  
Contractile Response ◽  
Ph Dependence ◽  
Membrane Properties ◽  
Buffer Concentration ◽  
Tension Development ◽  
Peak Tension ◽  
External Ph ◽  
Transmembrane Resistance

Following a period of intense repetitive stimulation (e.g., brief tetanic stimuli every second for 3 min), muscle isometric tension development is reduced by about 80%. This suppression is reversible at a high external pH (8.0) with a half time of 15–20 min, but if the external pH is low (6.4) or the buffer concentration is low, recovery is prevented. Inhibition of recovery is associated with a slowed rate of lactate loss, which may suggest that intracellular lactacidosis is the cause of the inhibition. Alternatively, a low external pH may affect recovery from fatigue quite independently of its effect on lactate efflux. The possibility that surface membrane properties are changed by fatigue in a pH-dependent fashion was examined by measuring the cable properties and action potentials of fatigued fibres at different external pH values. A low external pH during recovery from fatigue was shown to result in a prolonged membrane depolarization of 10–12 mV, an increased transmembrane resistance, and a prolonged action potential. At a high external pH transmembrane resistance is lowered by fatigue, the depolarization lasts only about 10–15 min, and there is a smaller effect on the action potential. While the fatigued fibre membrane does show a changed response that is dependent on external pH, it is not clear that this could be related to the suppression of contraction. Direct measurements of intracellular pH show a fall of about 0.4 to 0.5 pH units in the surface fibres following fatigue. This results from the lactic acid generated during activity. It is now clear that lactate crosses the membrane in association with protons and at least part of this flux is mediated by a specific carrier mechanism. Efflux is limited by the transmembrane pH gradient, which in turn depends on the extracellular buffer concentration in the diffusion limited space around the fibres. Intracellular lactacidosis in resting muscles can be generated by a reversal of the normal flux. Fibres can be loaded with lactate (L) by increasing the extracellular [H+][L−] product with a resultant fall in intracellular pH. Lactate loads similar to those seen in fatigued muscle simulate some but not all of the responses seen in the postfatigue state. The twitch is prolonged with a slow relaxation phase, an increased time to peak tension but with an increase in peak tension. The effects are reversible but usually result in a reduced contractile response following the washout. Tetanic tension is reduced, but the effect is small compared with that seen in fatigue. Relaxation from the tetanus is also slowed by the intracellular lactacidosis in a reversible fashion. It is concluded that intracellular lactacidosis is not the main cause of the suppressed tension found in the type of fatigue studied here but that the acidosis slows relaxation and may also prevent or slow some step in the transition from the fatigued to the normal state.

Measurement of the intracellular pH of Propionibacterium acnes: comparison between the fluorescent probe BCECF and 31P-NMR spectroscopy

1993 ◽  
Vol 39 (2) ◽  
pp. 180-186 ◽  
Author(s):  
C. M. Futsaether ◽  
B. Kjeldstad ◽  
A. Johnsson
Keyword(s):  
Nmr Spectroscopy ◽  
Fluorescent Probe ◽  
Intracellular Ph ◽  
Propionibacterium Acnes ◽  
31P Nmr Spectroscopy ◽  
Acetoxymethyl Ester ◽  
Positive Skin ◽  
Glucose Exposure ◽  
Ph Range ◽  
External Ph

The intracellular pH of the Gram-positive skin bacterium Propionibacterium acnes was determined using the pH-sensitive fluorescent probe 2′, 7′ bis-(2-carboxyethyl)-5-(and-6)carboxyfluorescein (BCECF). The probe was introduced into the bacteria using the membrane-permeable acetoxymethyl ester BCECF-AM. The intracellular pH of the bacteria was determined by establishing a relation between the fluorescence ratio 505/450 and pH using the ionophore nigericin. To verify the intracellular pH determined using BCECF, the results were compared with those obtained using 31P-NMR spectroscopy. The effects of different external pH values and glucose addition upon the intracellular pH were examined using BCECF and 31P-NMR. Good correlation was obtained between the two techniques. Propionibacterium acnes maintained a pH gradient, inside alkaline, in the external pH range 5.0–7.4, which inverted when the pH was > 7.5. At external pH ≥ 8.5, the intracellular pH was close to the external pH. Glucose exposure did not affect the intracellular pH. Rapid, transient intracellular acidification and alkalinization brought about using NaHCO3 and NH4Cl, respectively, could be detected using BCECF. A limitation encountered when using BCECF was BCECF leakage, which could significantly affect the results if not taken into account.Key words: intracellular pH, BCECF fluorescence, 31P-NMR spectroscopy, Propionibacterium acnes.

Intracellular pH and Survival of Listeria monocytogenes Scott A in Tryptic Soy Broth Containing Acetic, Lactic, Citric, and Hydrochloric Acids

1991 ◽  
Vol 54 (1) ◽  
pp. 15-19 ◽  
Author(s):  
POLLA S. ITA ◽  
ROBERT W. HUTKINS
Keyword(s):  
Acetic Acid ◽  
Listeria Monocytogenes ◽  
Intracellular Ph ◽  
Cell Number ◽  
Ph Gradient ◽  
Experimental Conditions ◽  
Log Reduction ◽  
Specific Effects ◽  
Lactic Acids ◽  
External Ph

To study the effect of citric, acetic, lactic, and hydrochloric acids on Listeria monocytogenes Scott A, growth, survival, and intracellular pH (pHin) values were determined during growth in a pH-controlled fermentation vessel. Under the experimental conditions, L. monocytogenes Scott A grown in tryptic soy (plus yeast extract) broth survived even when the pH was reduced to 3.5. For most acids, L. monocytogenes maintained a pH gradient (intracellular pH-external pH) of about 1.0 pH unit and a pHin near 5.0. When the citric and lactic acid-treated cells at pH values 3.5, 4.0, and 4.5 were incubated for a longer time (24 h), both the pH gradient and the pHin values decreased. Although citric and lactic acids were more effective in lowering the pHin, acetic acid had the greatest effect on cell survival. A greater than 4-log reduction in cell number occurred when L. monocytogenes was held in acetic acid-treated broth for 24 h at pH 3.5 even though the pHin was 5.0. The results suggest that inhibition of L. monocytogenes by acids is caused not by a decrease in the intracellular pH, per se, but rather by specific effects of undissociated acid species on metabolic or other physiological activities.

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