Intracellular pH and distribution of weak acids across cell membranes. A study of D‐ and L‐lactate and of DMO in rat diaphragm.

Roos, Albert de

doi:10.1113/jphysiol.1975.sp011000

Cited by 108 publications

(50 citation statements)

References 35 publications

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“…Our value of pHi in Ringer equilibrated with 5 % CO2, 95 % 02 at 370 C of 7 07 compares well with those obtained by Roos (1975) in rat diaphragm, using the DMO method. The mean value from the five control groups (n = 29) he quoted is 7410.…”

Section: Discussionsupporting

confidence: 72%

Micro‐electrode measurement of the intracellular pH and buffering power of mouse soleus muscle fibres.

1977

The Journal of Physiology

177

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SUMMARY1. The intracellular pH (pHi) of surface fibres of the mouse soleus muscle has been measured in vitro using recessed-tip pH-sensitive microelectrodes.2. In 5 % CO2 and pH 7 40, the mean pH1 was 7 07 + 0 007 (s.E. of mean) at 370 C and 7-23 + 0.01 at 280 C. The difference between these two values is the same as the change in neutral pH between 37 and 280 C.3. Alteration of the CO2 level at constant external pH caused a biphasic change in pH1 with a rapid displacement followed by a slower partial recovery. Because the recovery was incomplete, different stable pHi values were recorded at different CO2 levels, the higher the CO2 the lower the pHi. The differences in pHi were highly significant both at 37 and 280 C.4. Alteration of the CO2 level at constant external pH also changed the membrane potential (Em), an increase in CO2 leading to an increased Em. The dependence of Em on the CO2 level was much smaller in the fasttwitch muscle, extensor digitorum longus, than in soleus.5. Changing external pH, either by alteration of the bicarbonate or CO2level of the Ringer solution, caused pHi to change by a mean 38-7 % of the external pH change. The change in pHi was accomplished about 10 times more rapidly, and in the same direction, by altering CO2 than by altering the bicarbonate. 6. Application of external NH3 and NH+ caused a rapid intracellular alkalinization followed by a slower acidification. On removal of external NH3 and NH+, there was a large and rapid acidification, followed by a fairly rapid recovery in pHi.7. The size of the pH1 changes occurring on alteration of the CO2 level at both constant external pH and constant external bicarbonate, and on removal of external NH3 and NH+, suggests a non-CO2 buffering

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Section: Discussionsupporting

confidence: 72%

Micro‐electrode measurement of the intracellular pH and buffering power of mouse soleus muscle fibres.

1977

The Journal of Physiology

177

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“…3). In agreement with observations by others on lactic acid (Roos, 1975) or on other weak organic acids such as propionic acid (Boron, 1983;Grinstein, 1988), it is proposed that a fraction of lactic acid had entered the intracellular compart ment as nonpolar, undissociated compound. The in tracellular pH favors immediate dissociation of the compound on account of its low pK.…”

Section: Extracellular Acidosissupporting

confidence: 75%

Effects of Lactacidosis on Glial Cell Volume and Viability

Staub¹,

Baethmann²,

Peters³

et al. 1990

J Cereb Blood Flow Metab

159

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Summary: Effects of severe lactacidosis were analyzed in vitro by employment of C6 glioma cells and astrocytes from primary culture. The cells were suspended in a physiological medium, which was rendered acidotic by addition of lactic acid in rising concentrations. A pH range of 7.4-4.2 was studied under maintenance of isoto nicity and a normal electrolyte concentration of the me dium. Cell swelling was quantified by flow cytometry us ing an advanced Coulter system with hydrodynamic fo cusing. The method was also utilized for assessment of cell viability by exclusion of the fluorescent dye propid ium iodide. The volume of C6 glioma cells was found to increase if the pH was titrated to pH 6.8 or below. From this level downward, the extent of cell swelling depended on the degree of acidosis and the duration of exposure. For example, lactacidosis of pH 6.2 for 60 min led to an increase in cell size to 124.5% of normal, while pH 5.0 or 4.2 led to a cell size of 151.1 or 190.9%, respectively. A comparative analysis of the acidosis-induced cell swelling was made by using sulfuric acid. Swelling of C6 glioma at a given pH was only half of what was found when using lactic acid. This indicates specific swelling-inducing prop erties of lactic acid, while cell viability was not differently affected by both acids. Of the C6 glioma cells, 89.1 % were viable under control conditions at pH 7.4. The via bility remained unchanged down to pH 6.2. At pH 5.6, viability remained normal for 30 min, but it decreased to 73.4% after 60 min. Further lowering of pH to 5.0 or 4.6 respectively, decreased the number of viable cells to 47.8 Cerebral ischemia, seizures, and severe head in jury are associated with an enhancement of anaer obic metabolism resulting in intra-and extracellular lactacidosis (Siesj6, 198 1, 1988). Lactacidosis may be involved in the formation of cytotoxic brain edema and irreversible damage of nerve and glial

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“…The effect of ionic permeability on pHi transients was determined by Boron & DeWeer (1976) using flux equations and was shown, for our case, to depend on the ratio of the acid: anion permeabilities (PHA PA). Determining the propionic acid permeability is difficult, but Roos (1975) suggests that a value of 10-4 cm/sec is reasonable. This is consistent with the time course of the initial pHi changes observed in the present experiments.…”

Section: Discussionmentioning

confidence: 99%

The effects of chloride substitution on intracellular pH in crab muscle.

Sharp¹,

Thomas²

1981

The Journal of Physiology

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SUMMARY1. Intracellular pH (pHi) was measured in crab muscle fibres using pH-sensitive micro-electrodes. The mean stable pHi was 7-19+0-02 (S.E. of mean) and the corresponding mean membrane potential was -64-6+ 04 mV (S.E. of mean) at an external pH of 7-5.2. The effects on pHi of replacing 20 % (100 mM) of the external NaCl by the Na salts of various anions were examined. The anions of weak acids (pK'a > 4 5) caused large internal acidifications. The anions of strong acids (pK'a < 2-6) caused little or no change in pHi. The anions of acids with an intermediate pK' had varied effects on pHi. In particular salicylate (pK' = 2 97) was found to cause a large fall in pHi.3. Increasing the external pH reduced the effects of the anions of weak acids on pHi. It is argued that these effects are the result of the entry and subsequent dissociation of undissociated acid molecules.4. The results with propionate were quantified by comparing them with the effects of 5 % CO2 andwere found to be smaller than expected. It is suggested that this is the result of substantial membrane permeability to the propionate anion.

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Intracellular pH and distribution of weak acids across cell membranes. A study of D‐ and L‐lactate and of DMO in rat diaphragm.

Cited by 108 publications

References 35 publications

Micro‐electrode measurement of the intracellular pH and buffering power of mouse soleus muscle fibres.

Micro‐electrode measurement of the intracellular pH and buffering power of mouse soleus muscle fibres.

Effects of Lactacidosis on Glial Cell Volume and Viability

The effects of chloride substitution on intracellular pH in crab muscle.

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