Neutral carrier based calcium(2+)-selective electrode with detection limit in the sub-nanomolar range

Schefer, U.; Ammann, D.; Pretsch, E.; Oesch, U.; Simon, W.

doi:10.1021/ac00124a036

Cited by 210 publications

(104 citation statements)

References 30 publications

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“…The slope of the linear calibration curve was 25 mV/pCa in calibration buffers containing 10 mM EGTA, 1 mM MgCl 2 , 25 mM Tricine, 50 mM KCl, pH 7.2, and varying concentrations of CaCl 2 . This slope is close to previously published data (Schefer et al, 1986). In the range between 17 nM and 3 M the free Ca 2+ concentration was determined fluorimetrically using the ratiometric indicator dye Fura-2 (Grynkiewicz, Poenie & Tsien, 1985).…”

Section: Methodssupporting

confidence: 89%

Electrogenic Partial Reactions of the SR-Ca-ATPase Investigated by a Fluorescence Method

Butscher

Roudná

Apell

1999

Journal of Membrane Biology

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Abstract.A fluorescence method was adapted to investigate active ion transport in membrane preparations of the SR-Ca-ATPase. The styryl dye RH421 previously used to investigate the Na,K-ATPase was replaced by an analogue, 2BITC, to obtain optimized fluorescence changes upon substrate-induced partial reactions. Assuming changes of the local electric field to be the source of fluorescence changes that are produced by uptake/ release or by movement of ions inside the protein, 2BITC allowed the determination of electrogenic partial reactions in the pump cycle. It was found that Ca 2+ binding on the cytoplasmic and on the lumenal side of the pump is electrogenic while phosphorylation and conformational transition showed only minor electrogenicity. Ca 2+ equilibrium titration experiments at pH 7.2 in the two major conformations of the protein indicated cooperative binding of two Ca 2+ ions in state E 1 with an apparent half-saturation concentration, K M of 600 nM. In state P-E 2 two K M values, 5 M and 2.2 mM, were determined and are in fair agreement with published data. From Ca 2+ titrations in buffers with various pH and from pH titrations in P-E 2 , it could be demonstrated that H + binding is electrogenic and that Ca 2+ and H + compete for the same binding site(s). Tharpsigargin-induced inhibition of the Ca-ATPase led to a state with a specific fluorescence level comparable to that of state E 1 with unoccupied ion sites, independent of the buffer composition.

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Section: Methodssupporting

confidence: 89%

Electrogenic Partial Reactions of the SR-Ca-ATPase Investigated by a Fluorescence Method

Butscher

Roudná

Apell

1999

Journal of Membrane Biology

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“…Ca*+ ionophore is 1.8 mg N,N,N'N'-tetracyclohexyl-3-0x-apentanediamide (ETH129, Fluka 21193), with 118.1 mg 2-nitrophenyloctylether (o-NPOE, Fluka 73732), 1.1 mg potassium tetrakis(4-chlorophenyl)borate, and 59 mg PVC dis-solved in 2 ml of THE Inner filling solution is 0.01 M CaCl, (Schefer et al 1986). Methyltridodecylammonium nitrate (10.8 mg) (MTDDA-NO,, Fluka 91664) was used as ion exchange ligand for NO;, together with 117 mg 2nitrophenyloctylether…”

Section: Notesmentioning

confidence: 99%

High spatial resolution measurements in lake sediments with PVC based liquid membrane ion‐selective electrodes

Müller

Buis

Stierli

et al. 1998

Limnology & Oceanography

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Ion‐selective liquid membrane electrodes for Ca2+, CO32−, NH4+, NO3−, NO2−, and pH have been miniaturized and their characteristics evaluated in view of their application in sediment pore water of lakes. PVC membranes were prepared in polyethylene pipette tips with an end diameter of 0.6 mm. This is a simple method to produce inexpensive disposable ion‐selective electrodes for various applications. Detection limits were 1 µM for Ca2+, CO32−, NH4+, and NO3−, and 10 µM for NO2−. The pH sensor was linear in the pH range of 4–11. Selectivities for Ca2+, CO32− and pH are high enough for the application in seawater. The sensors for NH4+, NO3−, and NO2− in their low concentration range experience interferences from K+, SO42+, and HCO3−, respectively, in lake pore water. Reproducibility in pure solutions is between 20.2 and 20.6 mV, The applicability of the miniaturized sensors are demonstrated in measurements of concentration gradients across the sediment‐water interface in sediment cores of several lakes.

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“…Ca 2 + specific electrodes were calibrated using the same ionic background for calibration as used for Ca 2 + measurements. The poly (vinyl chloride) membrane of tbe electrode contained tbe recently developed neutral carrier ETH 129, which allows reliable measurements of ci+ down to the nanomolar range [18,19].…”

Section: Permeabilization Of Pancreatic Acinar Cells With Digitoninmentioning

confidence: 99%

Decavanadate displaces inositol 1,4,5-trisphosphate (IP3) from its receptor and inhibits IP3 induced Ca2+ release in permeabilized pancreatic acinar cells

et al. 1991

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-Inositol 1,4,5-trisphosphate (IP3) induced Ca 2 + release in digitonin permeabllized rat pancreatic acinar cells is specifically inhibited by decavanadate. The ca 2 + release induced with 0.18 flM IP3 is half maximally inhibited with approximately 5 flM decavanadate. Complete inhibition is achieved with around 20 flM decavanadate. Removal of decavanadate from the permeabilized cells fully restores sensitivity towards IP3, indicating the reversibility of the inhibition. Oligovanadate, which inhibits A TP dependent ca 2 + up1ake into intracellular stores, does not influence IP3 induced ca 2 + release. In order to reveal the mechanism underlying the effects of the different vanadate species, binding of IP3 to the same cellular preparations was investigated. We found that binding of IP3 to a high affinity receptor site (I

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Neutral carrier based calcium(2+)-selective electrode with detection limit in the sub-nanomolar range

Abstract: The authors thank Joel Harris for his helpful comments regarding the treatment of the data. This paper is dedicated to Cheves Walling on the occasion of his 70th birthday.

Cited by 210 publications

References 30 publications

Electrogenic Partial Reactions of the SR-Ca-ATPase Investigated by a Fluorescence Method

Electrogenic Partial Reactions of the SR-Ca-ATPase Investigated by a Fluorescence Method

High spatial resolution measurements in lake sediments with PVC based liquid membrane ion‐selective electrodes

Decavanadate displaces inositol 1,4,5-trisphosphate (IP3) from its receptor and inhibits IP3 induced Ca2+ release in permeabilized pancreatic acinar cells

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