The Role of Physico-Chemical Buffering and of Bicarbonate Transfer Processes in Intracellular pH Regulation in Response to Changes of Temperature in the Larger Spotted Dogfish (Scyliorhinus Stellaris)

1980 ◽  
Vol 85 (1) ◽  
pp. 99-110
Author(s):  
N. HEISLER ◽  
P. NEUMANN
Keyword(s):  
Intracellular Ph ◽  
Heart Muscle ◽  
White Muscle ◽  
Ph Regulation ◽  
Yield Data ◽  
Physico Chemical ◽  
Red Muscle ◽  
Intracellular Compartments

In order to evaluate the contributions of physico-chemical buffering to the adjustment of intracellular pH in response to changes of temperature in tissues of dogfish (Scyliorhinus stellaris), the CO2 equilibration method for the determination of intracellular buffer values was modified to yield data for the mathematical simulation of the intracellular compartments as closed buffer systems, and for the calculation of transmembrane bicarbonate transfer in vivo. The respective buffer values of imidazole-like and phosphate-like buffer substances were estimated to be about 39 and 11 in white muscle, 21 and 18 in red muscle and 27 and 10 mequiv/(pH.1 cell water) in heart muscle. In white muscle, the observed changes of intracellular pH can be explained by physico-chemical buffering and changes of PCO2. In red muscle and heart muscle considerable amounts of bicarbonate have additionally to be transferred across the cell membrane to achieve the temperature-dependent variations of pH observed in vivo.

Development and Pharmacokinetics Study of Antifungal Peptide Nanoliposomes by Liquid Chromatography-tandem Mass Spectrometry

2019 ◽  
Vol 15 (4) ◽  
pp. 312-318
Author(s):  
Shuoye Yang
Keyword(s):  
Mass Spectrometry ◽  
Biological Properties ◽  
Pharmacokinetic Property ◽  
Antifungal Peptide ◽  
Simple Liquid ◽  
Physico Chemical ◽  
Liquid Chromatography Tandem Mass ◽  
Pegylated Lipids

Background: The therapeutic ability and application of antifungal peptide (APs) are limited by their physico-chemical and biological properties, the nano-liposomal encapsulation would improve the in vivo circulation and stability. </P><P> Objective: To develop a long-circulating liposomal delivery systems encapsulated APs-CGA-N12 with PEGylated lipids and cholesterol, and investigated through in vivo pharmacokinetics. Methods: The liposomes were prepared and characterized, a rapid and simple liquid chromatographytandem mass spectrometry (LC-MS/MS) assay was developed for the determination of antifungal peptide in vivo, the pharmacokinetic characteristics of APs liposomes were evaluated in rats. Results: Liposomes had a large, unilamellar structure, particle size and Zeta potential ranged from 160 to 185 nm and -0.55 to 1.1 mV, respectively. The results indicated that the plasma concentration of peptides in reference solutions rapidly declined after intravenous administration, whereas the liposomeencapsulated ones showed slower elimination. The AUC(0-∞) was increased by 3.0-fold in liposomes in comparison with standard solution (20 mg·kg-1), the half-life (T1/2) was 1.6- and 1.5-fold higher compared to the reference groups of 20 and 40 mg·kg-1, respectively. Conclusion: Therefore, it could be concluded that liposomal encapsulation effectively improved the bioavailability and pharmacokinetic property of antifungal peptides.

Regulation of glycolytic enzymes during anoxia in the turtle Pseudemys scripta

1989 ◽  
Vol 257 (2) ◽  
pp. R278-R283 ◽  
Author(s):  
S. P. Brooks ◽  
K. B. Storey
Keyword(s):  
Heart Muscle ◽  
Glycogen Phosphorylase ◽  
White Muscle ◽  
Fold Increase ◽  
Glycolytic Enzymes ◽  
Phosphorylase Activity ◽  
Enzyme Form ◽  
Red Muscle ◽  
Km Value ◽  
Glycogen Phosphorylase Activity

The glycolytic enzymes glycogen phosphorylase, phosphofructokinase (PFK), and pyruvate kinase (PK) were assessed in liver, heart, red muscle, and white muscle of aerobic and 5-h anoxic turtles (Pseudemys scripta) for changes in total activity and kinetic parameters. Anoxia induced statistically significant changes in these glycolytic enzymes in each of the four organs assayed. Compared with normoxic controls, anoxic liver showed a 3.3-fold increase in glycogen phosphorylase activity, a 1.5-fold increase in the PFK I50 value for citrate (concentration that inhibits initial activity by 50%), a 1.5-fold increase in the PFK Michaelis constant (Km) value for fructose 6-phosphate (P), and an increased maximal activity of PK. Anoxic heart muscle showed a 2.6-fold decrease in glycogen phosphorylase activity and, for PFK, a 1.7-fold decrease in the Km value for ATP and a twofold increase in the I50 value for citrate. In anoxic white muscle, PFK showed a fivefold lower Km value for fructose-6-P and a threefold lower activator concentration producing half-maximal activation (A50) for potassium phosphate than the aerobic enzyme form. Changes in anoxic white muscle PK included a twofold increase in the Km value for ADP and a 1.7-fold decrease in the I50 value for alanine. In red muscle, anoxia affected only the Km value for ATP, which was 50% higher than the value for the aerobic enzyme form. Fructose 2,6-diphosphate (P2) levels also decreased in heart muscle and increased in red and white muscle during anoxia.(ABSTRACT TRUNCATED AT 250 WORDS)

Temperature effects on pH of mitochondria isolated from carp red muscle

1988 ◽  
Vol 254 (4) ◽  
pp. R611-R615 ◽  
Author(s):  
C. D. Moyes ◽  
L. T. Buck ◽  
P. W. Hochachka
Keyword(s):  
Intracellular Ph ◽  
Temperature Effects ◽  
Respiratory Control ◽  
Ph Gradient ◽  
Carp Cyprinus Carpio ◽  
Red Muscle ◽  
Effects Of Temperature ◽  
Increasing Temperature ◽  
Induced Changes

Mitochondria isolated from red muscle of carp (Cyprinus carpio) were used to investigate the effects of temperature and extramitochondrial pH (pHe) on the mitochondrial pH gradient and respiratory properties. Mitochondria from animals acclimated to 10 degrees C were isolated and incubated in KCl-based media with 0.2 mM lauroylcarnitine (C-12) as substrate. Maximal respiratory control ratios (RCR = state 3/state 4) were 16-18 between pH 6.7 and 7.4 at 10 degrees C; RCR values were 9-12 between pH 6.5 and 7.1 at 30 degrees C. Changes in RCR values were due primarily to changes in the state 3 rate (in the presence of ADP). Mitochondrial pH was determined by measuring 5,5-[2-14C]dimethyloxazolidine-2,4-dione distribution, using [14C]sucrose as an extramatrical marker. The pH gradient was inversely related to pHe. At any particular pHe, the mitochondrial pH gradient decreased with increasing temperature. However, if pHe was varied in the same manner that intracellular pH changes with temperature in vivo, the pH gradient was maintained constant at approximately 0.4 U at 10, 20, and 30 degrees C. These data suggest that carp red muscle mitochondria defend an appropriate mitochondrial pH gradient with temperature-induced changes in intracellular pH.

Effect of prior immobilization on muscular glucose clearance in resting and running rats

1988 ◽  
Vol 255 (4) ◽  
pp. E456-E462 ◽  
Author(s):  
J. Vissing ◽  
T. Ohkuwa ◽  
T. Ploug ◽  
H. Galbo
Keyword(s):  
Separate Determination ◽  
Mediated Action ◽  
Glucose Clearance ◽  
Red Muscle ◽  
Exercise Induced ◽  
And Control ◽  
Uptake And Metabolism

In vitro studies have shown that prior disuse impairs the glucose clearance of red skeletal muscle because of a developed insensitivity to insulin. We studied whether an impaired glucose clearance is present in vivo in 42-h immobilized muscles of resting rats and, furthermore, whether the exercise-induced increase in glucose clearance of red muscles is affected by prior immobilization. The 2-[3H]deoxy-D-glucose (2DG) bolus injection method was used to determine glucose clearance of individual muscles. At rest, glucose clearance was markedly impaired in rats with previously immobilized red muscles compared with nonimmobilized control rats (red gastrocnemius 0.46 +/- 0.02 vs. 0.99 +/- 0.08 and soleus 1.10 +/- 0.30 vs. 3.97 +/- 0.54 ml.min-1.100 g-1, P less than 0.005). During running (18 m/min), glucose clearance did not differ between muscles in previously immobilized and control rats. Insulin levels were always similar in the two groups and decreased during exercise. Intracellular nonphosphorylated 2DG was present in tissues with high glucose clearances. In conclusions, 42 h of immobilization markedly impairs glucose clearance of resting red muscle fibers in vivo. Apparently, physical inactivity in particular affects steps involved in insulin-mediated action that are not part of contraction-induced glucose uptake and metabolism. Presence of intracellular 2DG shows that separate determination of phosphorylated 2DG is necessary for accurate estimates of glucose metabolism and that accumulation of phosphorylated 2DG does not accurately reflect glucose transport.

scholarly journals Intracellular pH distribution as a cell health indicator in Saccharomyces cerevisiae

2011 ◽  
Vol 8 (64) ◽  
pp. 1635-1643 ◽  
Author(s):  
Thomas Aabo ◽  
Jesper Glückstad ◽  
Henrik Siegumfeldt ◽  
Nils Arneborg
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Plasma Membrane ◽  
Intracellular Ph ◽  
Ph Regulation ◽  
Metabolic Enzyme ◽  
Transport Mechanisms ◽  
Cell Functions ◽  
Internal Ph ◽  
Ratio Imaging

Internal pH regulation is vital for many cell functions, including transport mechanisms and metabolic enzyme activity. More specifically, transport mechanisms are to a wide degree governed by internal pH distributions. We introduce the term standard deviation of the intracellular pH (s.d.(pH int )) to describe the internal pH distributions. The cellular pH distributional response to external stress such as heat has not previously been determined. In this study, the intracellular pH (pH i ) and the s.d.(pH int ) of Saccharomyces cerevisiae cells exposed to supralethal temperatures were measured using fluorescence ratio imaging microscopy (FRIM). An exponential decline in pH i was observed after an initial small decline. For the first time, we report the use of FRIM for determining in vivo plasma membrane proton permeability coefficients in yeast. Furthermore, the exponential decay of pH i and the rupture of the cell plasma membrane, as measured by propidium iodide staining, at 70°C were not simultaneous but were separated by a significant temporal difference. Finally, a nonlinear relationship between the pH i and s.d.(pH int ) was found; i.e. the s.d.(pH int ) was significantly more sensitive to supralethal temperatures than pH i . s.d.(pH int ) is therefore proposed as an early health/vitality indicator in S. cerevisiae cells exposed to heat stress.

In Vivo Assimilation by Cod Muscle and Liver Tissue of Elemental Phosphorus from Polluted Sea Water

1970 ◽  
Vol 27 (6) ◽  
pp. 1131-1139 ◽  
Author(s):  
W. J. Dyer ◽  
D. F. Hiltz ◽  
R. G. Ackman ◽  
J. Hingley ◽  
G. L. Fletcher
Keyword(s):  
Lipid Content ◽  
Liver Tissue ◽  
White Muscle ◽  
Content Distribution ◽  
Sea Water ◽  
Elemental Phosphorus ◽  
Red Muscle ◽  
Seawater Environment ◽  
Exposure Levels

Cod rapidly assimilated elemental phosphorus from a seawater environment into their tissues. In a 16-hr exposure to a concentration of 20–80 ppb (parts per billion), phosphorus was concentrated a thousandfold in the liver (even more at lower exposure levels), from 10 to 25 times in white muscle, and about 50–100 times in red muscle. This distribution is roughly in proportion to lipid content. Distribution of the absorbed phosphorus is uniform throughout the white muscle of the fillet, thus facilitating sampling.

Regulation of VO2 in red muscle: do current biochemical hypotheses fit in vivo data?

1989 ◽  
Vol 256 (4) ◽  
pp. R898-R906 ◽  
Author(s):  
R. J. Connett ◽  
C. R. Honig
Keyword(s):  
Intracellular Ph ◽  
Adenine Nucleotide ◽  
Energy State ◽  
Adenine Nucleotides ◽  
Wide Range ◽  
Glycolytic Intermediates ◽  
Red Muscle ◽  
Ph Range

Observations used to test biochemical models of the regulation of O2 consumption (VO2) by cytosolic phosphate energy state must include a change in intracellular pH and/or a change in the adenine nucleotide or phosphate pools [Connett, R. J. Analysis of metabolic control: new insights using a scaled creatine kinase model. Am. J. Physiol. 254 (Regulatory Integrative Comp. Physiol. 23): R949-R959, 1988]. Data were collected over a wide range of energy turnover from canine muscles in situ. Intracellular PO2, glycolytic intermediates, adenine nucleotides, creatine, phosphocreatine (PCr), phosphate, and intracellular pH were determined for each muscle. PO2 was used to eliminate muscles in which VO2 could have been O2 limited (PO2 less than 0.5 Torr). This removed an important source of heterogeneity. Because adenine nucleotide and phosphate pools were constant relative to the creatine pool, discrimination among models depended solely on pH. The observed pH range from 7.2 to 5.9 did not permit separation of [PCr] from log[( ATP4-]/[ADP3-][H2PO4-]) (phosphorylation potential) as a regulatory parameter for VO2. However, [ADP] could be eliminated as an independent regulator. Because 90% of variability in VO2 was accounted for by phosphate energetics, an independent redox component must be small when intracellular PO2 greater than 0.5 Torr.

Dibutyryl cyclic AMP increases phosphodiesterase activity in the rat heart

1984 ◽  
Vol 62 (9) ◽  
pp. 1225-1230 ◽  
Author(s):  
Warren K. Palmer ◽  
Sylvia Doukas
Keyword(s):  
Cyclic Amp ◽  
Rat Heart ◽  
White Muscle ◽  
Supernatant Fraction ◽  
Red Muscle ◽  
Injection Protocol ◽  
Fast Twitch ◽  
Dose Dependent ◽  
Increased Activity

The influence of increasing the in vivo concentration of cyclic AMP on the activity of cyclic nucleotide phosphodiesterase (PDE) in rat heart was investigated. One, three, and five hourly injections of 5.0 mg dibutyryl (Bt2) cyclic AMP significantly increased the activity of PDE in the supernatant fraction of rat heart using 1.0 μM cyclic AMP as the assay substrate concentration. When 100 μM cyclic AMP was used in the assay reaction, increases in enzymes activity were seen following five and eight nucleotide injections. The nucleotide-induced increase in PDE activity was dose dependent. When the five-injection protocol was used, PDE activity remained elevated for at least 4 h, while activity had returned to control levels within this time when two hourly injections were used. The nucleotide stimulation of PDE activity was blocked by cycloheximide. Five hourly infections of Bt2 cyclic AMP increased PDE activity in the liver and fast-twitch red muscle. A reduction in PDE activity in fast-twitch white muscle was seen following nucleotide injections. These findings are consistent with the hypothesis that prolonged elevations in the intracellular concentration of cyclic AMP cause an elevation in myocardial PDE activity. The increased activity seems to be the result of protein synthesis. These data suggest that cyclic AMP contributes significantly in regulating its own metabolism in the rat heart.

scholarly journals Myocardial intracellular pH in a perfused rainbow trout heart during extracellular acidosis in the presence and absence of adrenaline

1986 ◽  
Vol 125 (1) ◽  
pp. 347-359 ◽  
Author(s):  
A. P. Farrell ◽  
C. L. Milligan
Keyword(s):  
Rainbow Trout ◽  
Intracellular Ph ◽  
Ph Regulation ◽  
Respiratory Acidosis ◽  
Mechanical Efficiency ◽  
Extracellular Ph ◽  
Salmo Gairdneri ◽  
Intracellular Ph Regulation ◽  
Extracellular Acidosis

Myocardial intracellular pH was measured in a perfused rainbow trout, Salmo gairdneri, with DMO (5,5-dimethyl-2,4-oxazlidinedione), to test the hypothesis that catecholamines promote active regulation of myocardial pH in order to protect contractility during a respiratory acidosis comparable to that observed after exercise. Under control conditions (extracellular pH = 8.0; PCO2 = 2 Torr), myocardial pH was 7.53 +/− 0.01 (N = 5). Acidosis (extracellular pH = 7.45; PCO2 = 8.6 Torr) reduced contractility, mechanical efficiency and intracellular pH (7.25 +/− 0.04), but did not affect myocardial O2 consumption. The addition of 0.5 mumol l-1 adrenaline during extracellular acidosis prevented the loss of contractility, restored mechanical efficiency, but did not change intracellular pH significantly. Thus, adrenaline enabled cardiac contractility to recover, without intracellular pH regulation, possibly by modulation of sarcolemmal calcium changes. The absence of a myocardial acidosis after exercise in vivo is discussed with respect to possible intracellular pH regulation via lactate uptake and metabolism.

A novel FbFP-based biosensor toolbox for sensitive in vivo determination of intracellular pH

2017 ◽  
Vol 258 ◽  
pp. 25-32 ◽  
Author(s):  
Christian Rupprecht ◽  
Marcus Wingen ◽  
Janko Potzkei ◽  
Thomas Gensch ◽  
Karl-Erich Jaeger ◽  
...  
Keyword(s):  
Intracellular Ph
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