An Organic Cation-Selective Electrode: Potentiometric Determination of Acetylcholine Activity

Electroretinogram (ERG) and extracellular potassium activity (Kõ measurements were carried out in isolated superfused rabbit eyecup preparations under control conditions and during the application of pharmacological agents that selectively modify the light-responsive retinal network. Light-evoked Ko changes in the rabbit (E-type) retina resemble those previously described in amphibian (1-type) retinas. Different components of the lightevoked Ko changes can be distinguished on the bases of retinal depth, V vs . log I properties, and their responses to pharmacological agents . We find two separable sources of light-evoked increases in extracellular K+: a proximal source and a distal source . The properties of the distal light-evoked Ko increase are consistent with the hypothesis that it initiates a K+-mediated current through Muller cells that is detected as the primary voltage of the electroretinographic b-wave . These experiments also support previous studies indicating that both the corneal-positive component of c-wave and the corneal-negative slow P1I1 potential result from K+-mediated influences on, respectively, the retinal pigment epithelium and Muller cells.

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“…in place of the K+ exchanger (Baum, 1970) . The solute for the ACh exchanger was synthesized and kindly provided for our use by Dr. George Baum .…”

Section: Microelectrodesmentioning

confidence: 99%

Extracellular K+ activity changes related to electroretinogram components. II. Rabbit (E-type) retinas.

Dick¹,

Miller²,

Bloomfield³

1985

The Journal of General Physiology

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“…Although Baum (1970) indicated a nonideal response to quaternary amines for this exchanger, this can be corrected by tailoring the reference solution for the amine being assayed. In general, reference solutions were composed of 1-2 M KCI and 1-2 M quaternary-ion-of-interest.…”

Section: Methodsmentioning

confidence: 99%

Characterization of drug iontophoresis with a fast microassay technique

Dionne¹

1976

Biophysical Journal

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The iontophoretic release of drugs from micropipettes into free (Ringer's) solution was described using an ion-selective microelectrode assay method. This characterization, with a temporal resolution of 20 ms, showed that the equilibrium rate of drug transport was not linearly proportional to release current; the departure from linearity was increased by backing current and the result was demonstrated with analytically derived drug release functions. The general relation between the drug transport rate and release current was independent of the specific drug or pipette resistance; no functional relation was observed that might quantitatively predict this dependence without prior use of the assay. The diffusion coefficients at 25 degrees C in frog Ringer's of the drugs used in this study, all neuromuscular agonists, were determined: all values X 10(6) cm2/s; acetylcholine 6.11 +/- 0.30; carbamylcholine 7.44 +/- 0.34; 3-(m-hydroxyphenyl) prophyltrimethyl ammonium 5.79 +/- 0.13.

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“…Recent analytical applications of these microinterfaces have resulted in construction of gelsolidified probes. The advantage of such a modification is ease of handling (44)(45)(46)(47).…”

Section: Microinterface Between Two Immiscible Solutionsmentioning

confidence: 98%

Interfacial Ion Transport between Immiscible Liquids

Vanýsek

1994

Advances in Chemistry

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The interface between two immiscible liquids is used as a characteristic boundary for study of charge equilibrium, adsorption, and transport. Interfacial potential differences across the liquid-liquid boundary are explained theoretically and documented in experimental studies with fluorescent, potential-sensitive dyes. The results show that the presence of an inert salt or a physiological electrolyte is essential for the function of the dyes. Impedance measurements are used for studies of bovine serum albumin (BSA) adsorption on the interface. Methods for determination of liquid-liquid capacitance influenced by the presence of BSA are shown. The potential of zero charge of the interface was obtained for 0-200 ppm of BSA. The impedance behavior is also discussed as a function of pH. A recent new approach, using a microinterface for interfacial ion transport, is outlined. Liquid-Liquid Interfaces and ElectrochemistryInterfaces between two immiscible solutions with dissolved electrolytes, which are most interesting to workers in several disciplines, cover theoretical physical electrochemistry and analytical applications for sensor design. These interfaces are used in interpretation of processes that occur in biological membranes and in biological systems. The interface between two immiscible electrolyte solutions was studied for the first time at least 100 years ago by Nernst (I), who performed the experiments that provide the theoretical basis for current potentiometric and voltammetric studies of interfaces. In 1963, Blank and Feig (2) suggested that an interface between two immiscible liquids could be used as a model (at least as a crude approximation) for 0065-2393/94/0235-0055$09.26/0

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An Organic Cation-Selective Electrode: Potentiometric Determination of Acetylcholine Activity

Cited by 50 publications

References 6 publications

Extracellular K+ activity changes related to electroretinogram components. II. Rabbit (E-type) retinas.

Extracellular K+ activity changes related to electroretinogram components. II. Rabbit (E-type) retinas.

Characterization of drug iontophoresis with a fast microassay technique

Interfacial Ion Transport between Immiscible Liquids

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