Sodium–calcium exchange influences the response to endothelin-1 in lens epithelium
| Autor: | Mansim C. Okafor, Shigeo Tamiya, Nicholas A. Delamere |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
Indoles
Endothelin A Receptor Antagonists Swine Physiology Bepridil Blotting Western chemistry.chemical_element Calcium-Transporting ATPases Calcium Sodium-Calcium Exchanger Ouabain chemistry.chemical_compound Lens Crystalline medicine Animals Calcium Signaling Molecular Biology Calcium signaling Endothelin-1 Chemistry Ionomycin Sodium Epithelial Cells Cell Biology Receptor Endothelin A Immunohistochemistry Endothelin 1 Calcium ATPase Microscopy Fluorescence Biochemistry Biophysics Fura-2 Endothelin receptor Cyclopiazonic acid Oligopeptides medicine.drug |
| Zdroj: | Cell Calcium. 34:231-240 |
| ISSN: | 0143-4160 |
| DOI: | 10.1016/s0143-4160(03)00085-x |
| Popis: | Studies were conducted to examine the possible involvement of Na+-Ca2+ exchanger in determining the magnitude of the endothelin-1 (ET-1)-receptor-mediated calcium signal in porcine lens epithelial cells. Cytoplasmic calcium concentration was measured in primary cultured cells loaded with Fura-2. ET-1 (100 nM) caused cytoplasmic calcium to increase transiently to approximately 250 nM from a baseline of approximately 65 nM. The calcium increase decayed to a sustained plateau 35-45 nM above the baseline. Both the peak and plateau component of the ET-1 calcium response were abolished by PD145065, an ET receptor antagonist, and by cyclopiazonic acid (CPA) (10 microM). In calcium-free bathing solution, only the plateau was abolished. In the presence of ouabain, low-sodium bathing solution or bepridil, a sodium-calcium exchange inhibitor, peak height more than doubled. Bepridil also increased the peak height of the calcium response to ATP. The half-time for decay of the ET-1 and ATP calcium peak was increased several folds by bepridil, ouabain and low-sodium conditions. Measurements of ionomycin-releasable calcium suggested calcium store size was not increased in bepridil-treated cells. Taken together findings suggest inhibition of sodium-calcium exchange increases the magnitude of the receptor-initiated store-release phase of the ET-1 calcium signaling response as the result of impaired calcium clearance from the cytoplasm. |
| Databáze: | OpenAIRE |
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