Characteristics of chloride currents activated by noradrenaline in rabbit ear artery cells
| Autor: | T Amédée, W. A. Large, Q Wang |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
medicine.medical_specialty
4-Acetamido-4'-isothiocyanatostilbene-2 2'-disulfonic Acid Physiology Sodium chemistry.chemical_element Cell Separation 4 4'-Diisothiocyanostilbene-2 2'-Disulfonic Acid Calcium Chloride Ion Channels Muscle Smooth Vascular Norepinephrine chemistry.chemical_compound Chlorides Chloride Channels Internal medicine medicine Animals Patch clamp Reversal potential Membrane potential Membrane Proteins Ear Arteries Electrophysiology Endocrinology chemistry DIDS Chloride channel Biophysics Rabbits Research Article medicine.drug |
| Zdroj: | The Journal of Physiology. 428:501-516 |
| ISSN: | 0022-3751 |
| DOI: | 10.1113/jphysiol.1990.sp018224 |
| Popis: | 1. Responses to noradrenaline were studied in isolated rabbit ear artery cells with the nystatin method of whole-cell patch-clamp recording. With this technique it was possible to obtain reproducible responses to noradrenaline which was not possible with traditional whole-cell recording. 2. With NaCl as the major constituent of the bathing solution (potassium-free pipette and external solutions) the reversal potential (Er) of the noradrenaline-evoked current was about 0 mV. When external chloride was replaced by thiocyanate, iodide, nitrate and bromide, Er was shifted to more negative potentials which indicates that a chloride conductance increase contributes to the current activated by noradrenaline. 3. When sodium was substituted by Tris, N-methyl-D-glucamine, choline or barium, Er of the noradrenaline-evoked current did not alter. This result suggests that a cation conductance is not implicated in the response to noradrenaline recorded with the nystatin method of whole-cell recording. 4. The chloride current activated by noradrenaline was blocked by the selective alpha 1-adrenoceptor antagonist prazosin but was not affected by the alpha 2-adrenoceptor antagonist yohimbine. 5. When cells were exposed to zero calcium bathing solutions the amplitude of the current elicited by noradrenaline was unaffected when measured within 1-2 min in zero calcium conditions. Continued exposure to 0 Ca + 1 mM-EGTA solution reversibly abolished the chloride current to noradrenaline. 6. In the presence of caffeine, which releases Ca2+ from internal stores and itself induced an inward current (at a holding potential of -50 mV), noradrenaline did not elicit a current. These data suggest that the chloride current evoked by noradrenaline results from an increase in intracellular concentration of calcium derived from internal stores. 7. The chloride channel blocking agents 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS; 0.5 mM) and furosemide (0.5 mM) produced partial reduction of the noradrenaline-evoked chloride current whereas 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulphonic acid (SITS), anthracene-9-carboxylic acid (A-9-C) and picrotoxin were ineffective in concentrations of up to 0.5 mM. However DIDS and furosemide were non-selective blockers as both agents were more effective against the adenosine triphosphate-induced cation current. |
| Databáze: | OpenAIRE |
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