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PubMed1976

Derivatives of 1-naphthyl ethylenediamine dihydrochloride for standardization of direct-bilirubin assays done with the Technicon "SMAC".

The Jendrassik--Groff assay for direct bilirubin was adapted for analysis rates of 150/h on the Technicon "SMAC" continuous-flow analyzer. This requires development of a standard that is compatible with the other 19 channels on this analyzer. N-1-Naphthyl ethylenediamine dihydrochloride has been used for standardization of direct bilirubin assays, but we found it to be unsuitable because values for potassium are falsely elevated when potassium is determined with a valinomycin ion-selective electrode. This interference can be eliminated by alkylating the aliphatic amine group in the standard. The resulting compounds undergo the coupling reaction in the same way as the original compound and function equally well as standards for the direct bilirubin reaction. The only limitation of these analogs is their decreased solubility at physiological pH in some cases. Thus only certain alkyl groups are suitable.

Autoanalysis↗
PubMed1992

[Extracellular pH, [K+] and synaptic transmission in the dorsal horn of spinal cord of rats in hypercapnia].

In rats anaesthetized with +-chloralose the changes in extracellular pH and K+ in spinal cord dorsal horn were studied using pH and K+ ion-selective electrodes. The addition of 20% CO2 into inhaled air decreased the basal level of [pH]0 from 7.35 +/- 0.01 to 6.78 +/- 0.09 pH units and increased the basal level of [K+]0 from 3.1 +/- 0.1 to 5.14 +/- 0.8 mM. Electrocutaneous supramaximal (10 mA) simulation of both hind paws with the frequency 30 and 100 Hz induced the shift in the concentration of H+ and K+ by 0.15-0.2 unit and 2-2.5 mM, respectively. Under hypercapnia this shift of pH decreased by 36.9 +/- 8.5% at 30 Hz frequency of electrocutaneous stimulation and by 41.9 +/- 6.1% at 100 Hz frequency. The K+ shift decreased by 11.5 +/- 1.3% and by 17.3 +/- 1.5% under similar conditions. Hypercapnia induced by addition of 20% CO2 into inhaled air decreased also the focal potential amplitude by 16.8 +/- 4%. Thus, hypercapnia induces the increase of [K+]0 and [pH]0 and the decrease of recorded indicators in response to electrocutaneous stimulation. Total depression of synaptic transmission and analgetic effect occur due to these changes of ions distribution.

Animals↗
PubMed1992

Urinary salt titrator stick: a useful and quick estimate of dietary sodium intake?

Repeated measures of urinary salt excretion are the best compromise between reliability and convenience for estimating dietary salt intake. In order to assess the accuracy of the Uropaper urinary salt titrator stick (giving discrete readings of 4, 6, 8, 10, 12 or 14 g/l of NaCl), 312 urine samples were analysed both with the stick and with an ion-selective electrode. There was a good stick-electrode correlation in all the 312 samples (r = 0.84). With a tolerance of +/- 1 g/l, the percentages of correct estimations dropped from 82% to 33% with increasing concentrations of NaCl in the urinary sample. For NaCl concentrations greater than 8 g/l (137 mmol/l) the error in the stick measurement consisted almost exclusively of overestimation of the electrode readings. These results were unaffected by the concentration of urinary potassium. No discrepancies were found among three different readers. This stick is easy to use and measures, with reasonable accuracy, low urinary NaCl concentrations. It could be useful for self-monitoring during low NaCl diets.

Administration, Oral↗
PubMed1992

[Solute movement across the round window membrane in comparison with that across the blood-labyrinth barrier].

The permeability of the normal round window membrane of the guinea pig to trimethylphenylammonium (TMPA) was assessed using ion-selective electrodes and compared with the rate of TMPA entry from the systemic blood circulation into the scala tympani (ST) of the cochlea across the so-called blood-labyrinth barrier. While the round window niche was irrigated with artificial perilymph containing 1 mM TMPA, the TMPA concentration in ST of the basal turn rose rapidly so as to reach 20-50% of the irrigating medium concentration in one hour. Following this procedure, the concentration declined significantly faster when the niche was subsequently irrigated with TMPA-free artificial perilymph than when the niche was left free of any fluid. This result shows that the membrane is fairly permeable to TMPA in both directions. Furthermore, TMPA entry from blood to STs of the basal and third turns was observed while the plasma TMPA concentration was maintained at about 0.5 mM by continuous intravenous infusion of isotonic 50 mM TMPA medium (1 part 150 mM TMPA + 2 parts lactated Ringer solution). TMPA appeared to distribute evenly from the blood to both turns at a much slower rate than across the round window membrane. In another experiment, the round window niche was irrigated with TMPA-free artificial perilymph during the intravenous infusion of 50 mM TMPA medium. The TMPA concentration increase in ST of the basal turn was greatly suppressed, whereas that of the third turn was not affected for at least an hour.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

[Coupled transport of K+, Cl-, H+ and OH- ions in a liposome suspension].

By means of the system of ion-selective electrodes the coupling transport of K+, H+ and Cl- ions in liposome suspension was studied. Nigericin and tributyl tin (TBT) were used as inductors of cation and anion exchange. Effect of pH gradient created on the membrane on ionic transport was studied. The latter was shown to control the antiport exchange of both, cations and anions. At the joint effect of nigericin and TBT the yield of K+ and Cl- ions from liposomes independent of the pH gradient was observed.

Biological Transport↗
PubMed1978

Measurement of free calcium ion in capillary blood and serum.

We describe a new calcium ion-selective electrode for measurement of the substance concentration of free calcium ion [Ca2+] in the plasma phase of whole blood and in serum at 37 degrees C. A sample volume of 50 microliter suffices to obtain simultaneous values of pH and [Ca2+]. We found the within-series analytical standard deviation for serum to be 0.013 mmol/litre (CV, 1.1%) and day-to-day precision to be 0.022 mmol/litre (CV, 1.7%). The reference interval for [Ca2+] (at pH 7.40) in serum was found to be 1.184 +/- 0.054 mmol/litre (2 SD) from measurements on sera from 121 healthy blood donors. Measurements on capillary blood from 29 healthy volunteers gave a mean (+/- 2 SD) value for [Ca2+] (at pH 7.40) of 1.22 +/- 0.072 mmol/litre.

Bicarbonates↗
PubMed1979

[New diagnostic examinations in patients with urinary calculi, taking into consideration primary hyperparathyroidism].

The serum levels of total calcium and anorganic phosphate have been the leading parameters in the diagnosis of primary hyperparathyroidism. In addition to these, it is now possible to measure ionized calcium (Ca++) by an ion-selective electrode and parathormone (PTH) by C- and N-terminal radioimmunoassays (RIA). Whereas Ca++ determination and C-terminal PTH RIA represent a diagnostic progress, this can not be claimed for the N-terminal PTH RIA in peripheral venous blood especially in border-line cases.

Calcium↗
PubMedDate not supplied

[K-strophanthin-beta complexing with calcium, magnesium and dysprosium ions].

Nuclear magnetic resonance, microcalorimetry and the use of the ion-selecting electrode evidenced that k-strophanthine-beta forms complexes with the calcium, magnesium and disprosium ions. Changes in the position of the k-strophanthine-beta carbohydrate parts and aglycones signals bear witness to their participation in the complexing.

Calcium↗
PubMed1979

On-line continuous potentiometric measurement of potassium concentration in whole blood during open-heart surgery.

We describe a flow-through system with an ion-selective electrode for measurement of blood potassium ion concentration, continuously and on-line off the extracorporeal blood circulation in an operating theater during human open-heart surgery. Comparison measurements were made with the SMA flame photometer (blood plasma) and an Orion SS 30 sodium/potassium analyzer (whole blood). The potassium concentration values obtained with the flow-through system agree well with the ones determined with the flame photometer. The time delay of the measurement with the flow-through system was relatively long (2 min) but delays of only 10--20 s seem feasible. Short time delays can deepen insight and simplify rational treatment under surgery conditions.

Autoanalysis↗
PubMed1977

Differential effects of cortical speading depression on epileptic foci induced by various convulsants.

Interaction between epileptic foci and spreading depression (SD) was studied in the cerebral cortex of rats anesthetized with Nembutal. At comparable discharge rates, picrotoxin and penicillin caused complete and partial SD blockade respectively, strychnine and Metrazol were ineffective and Aldactone facilitated SD. Conversely, the duration of SD-induced blockade of epileptic activity was maximal for Aldactone and minimal for picrotoxin. Treatment of the picrotoxin focus with tetrodotoxin (10(-4)M) reduced the discharge rate and reinstated SD propagation into the focus. [K+]e measured with ion-selective K+ electrodes 1 mm below the cortical surface increased to 8 mM in penicillin foci blocking SD and remained below 5 mM in Aldactone foci. It is concluded that the differential effect of various convulsants on SD propagation depends on the potassium concentration in the depth of the focus rather than on the discharge rate or on the mechanism of the the epileptogenic effect.

Animals↗
PubMed1992

Intracellular and extracellular chloride ions in the horizontal cells of the stingray retina.

Intracellular and extracellular concentrations of chloride ([Cl-]i, [Cl-]o) ions in the horizontal cells of the stingray retina were studied by means of ion-selective microelectrodes. The electrodes used were of the double-barreled type and Corning's #477315 resin was used as the exchanger. The average [Cl-]o and [Cl-]i in the L-type cells were 320 and 130 mM, respectively (n = 37), and the equilibrium potential (ECl) was calculated as -23.3 mV. In some cases, dark membrane potentials were more positive than the ECl. With white light stimulus, the membrane hyperpolarized to a more negative level than ECl. Based on the experiments described above, the hypothesis that the hyperpolarizing response of horizontal cells is due to the permeability change of the membrane to chloride ion was excluded in the stingray retina.

Animals↗
PubMed1978

[Ammonium-selective disc-electrode with the carrier-antibiotic nonactin. A method for the continuous enzymatic, electrochemical determination of urea, I (author's transl)].

An ammonium-selective disc-electrode is described; the membrane consists of a polyvinylchloride-matrix with an active phase of nonactin in tris (2-ethylhexyl)phosphate and diphenyl ether as the ion-selective plastic. One side of the membrane is in contact with the solution to be measured and the other with the front surface of a platinum wire, which is enclosed in acrylic glass. This arrangement results in a very low drift potential.

Anti-Bacterial Agents↗
PubMed1992

The nss mutation or lanthanum inhibits light-induced Ca2+ influx into fly photoreceptors.

Ion-selective calcium microelectrodes were inserted into the compound eyes of the wild-type sheep blowfly Lucilia or into the retina of the no steady state (nss) mutant of Lucilia. These electrodes monitored light-induced changes in the extracellular concentration of calcium (delta[Ca2+]o) together with the extracellularly recorded receptor potential. Prolonged dim lights induced a steady reduction in [Ca2+]o during light in the retina of normal Lucilia, while relatively little change in [Ca2+]o was observed in the retina of the nss mutant. Prolonged intense light induced a multiphasic change in [Ca2+]o: the [Ca2+]o signal became transient, reaching a minimum within 6 s after light onset, and then rose to a nearly steady-state phase below the dark concentration. When lights were turned off, a rapid increase in [Ca2+]o was observed, reaching a peak above the dark level and then declining again to the dark level within 1 min. In analogy to similar studies conduced in the honeybee drone, we suggest that the reduction in [Ca2+]o reflects light-induced Ca2+ influx into the photoreceptors, while the subsequent increase in [Ca2+]o reflects the activation of the Na-Ca exchange which extrudes Ca2+ from the cells. In the nss mutant in response to intense prolonged light, the receptor potential declines to baseline during light while the Ca2+ signal is almost abolished, revealing only a short transient reduction in [Ca2+]o. Application of lanthanum (La3+), but not nickel (Ni2+), into the retinal extracellular space of normal Lucilia mimicked the effect of the nss mutation on the receptor potential, while complete elimination of the Ca2+ signal in a reversible manner was observed. The results suggest that La3+ and the nss mutation inhibit light-induced Ca2+ influex into the photoreceptor in a manner similar to the action of the trp mutation in Drosophila, which has been shown to block specifically a light-activated Ca2+ channel necessary to maintain light excitation.

Animals↗
PubMed1976

Physicochemical properties of a liquid ion exchanger microelectrode and its application to biological fluids.

Double-barreled potassium or chloride ion-selective microelectrodes were constructed using a liquid ion exchanger. Technical details of the fabrication of double-barreled microelectrodes, having a PD sensor as one barrel and an ionic sensor as the other, are described. The sensitivity of K+ or CI- ion-selective microelectrodes exhibited an approximately Nernstian response over a temperature range of 7 degrees-37 degrees C, and the electromotive force (EMF) was stable within +/- mV for a few hours. The rise time was less than 1 sec. The effect of pH on the electrode response was negligible over a physiological range of pH 5.6 to 7.8. The selectivity constants of the K+ microelectrode to other cations were 0.011 for Na+, 0.200 for NH+4, and less than 0.002 and 0.001 for Ca++ and Mg++, respectively, while that of the CI- microelectrode was 0.067 for HCO-3. Glucose or urea has no effect on the EMF. Protein has a significant effect on ion exchanger membrane only when the concentration of the tested ion is low and protein is high. On the basis of this background the determination of K+ and CI- activity was carried out both in vivo and in vitro on several biological samples, such as serum, tissue and cellular fluids, and other protein-containing fluids. The values obtained with the microelectrode were consistent with those obtained with the other conventional methods or with the current theory on electrolyte solutions. These results were taken to assure the practical application of these electrodes to biological studies in many fields.

Animals↗
PubMed1978

Intracellular gradients of ion activities in the epithelial cells of the Necturus gallbladder recorded with ion-selective microelectrodes.

In Necturus gallbladder epithelial cells the intracellular electrical potential, as recorded with microelectrodes, varied from -28 mV in the mucosal end to about -50 mV in the serosal end of the transporting cell. The Na+ activity varied concurrently from about 39 mM to between 8 and 19 mM. Thus, within the cell both the recorded electrical and chemical gradients caused Na+ to move towards the serosal end. Serosal addition of ouabain (5 X 10(-4) M) caused the intracellular Na+ activity to attain electrochemical equilibrium within 30 min. However, the intracellular electrical potential gradient was only slowly affected. In cells from animals stored at 5 degrees C, the Cl- activity varied from about 55 mM in the mucosal end to 28 mM in the serosal end, and the K+ activity from 50 mM to between 95 and 131 mM. Both ions were close to electrochemical equilibrium within the cytoplasm but were too concentrated to be in equilibrium with the mucosal solution. Bubbling CO2 through the mucosal solution caused the intracellular gradients to vanish. When Na+ in the bathing solutions was exchanged for K+, the intracellular electrical potential became roughly constant at about -5 mV. The Cl- activity became constant in 65 mM, and the K+ activity became constant at 109 mM, both close to equilibrium with the mucosal solution. The Na+ activity was reduced to about 1 mM. The ratio of cytoplasmic resistivities between cells bathed in K+-rich saline to cells bathed in Na+-rich saline was measured by means of triple-barreled electrodes and compared to the same ratio as assessed from the activity measurements. The two values were equal only if one assumes the mobility of Na+ inside the cell to be less than 1/10 of the mobility of K+ or Cl-. The same conclusion was reached by comparing the intracellular Na+ flux calculated from the gradient of electrochemical potential to that flux assess from the net solute absorption. Animals kept at 15 degrees C had lower intracellular Na+ activities, higher Cl- and K+ activities, and higher rates of absorption than animals stored at 5 degrees C. Finally, the degree to which the intracellularly recorded electrical and chemical potentials could reflect an electrode artefact is discussed.

Animals↗