Ca2+ entry activated by emptying of intracellular Ca2+ stores in ileal smooth muscle of the rat
| Autor: | Kazue Kawai, Toshio Ohta, Yoshikazu Nakazato, Shigeo Ito |
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| Rok vydání: | 1995 |
| Předmět: |
Male
medicine.medical_specialty Indoles Carbachol Fura-2 chemistry.chemical_element Calcium-Transporting ATPases Calcium chemistry.chemical_compound Ileum Isometric Contraction Internal medicine Muscle tension medicine Animals Channel blocker Rats Wistar Pharmacology Manganese Chemistry Muscle Smooth Rats Endocrinology Metals medicine.symptom Cyclopiazonic acid Intracellular Research Article medicine.drug Muscle contraction |
| Zdroj: | British Journal of Pharmacology. 114:1165-1170 |
| ISSN: | 0007-1188 |
| Popis: | 1. The effects of depletion of intracellular Ca2+ stores on muscle tension and the intracellular Ca2+ concentration ([Ca2+])i were studied in fura-2 loaded longitudinal smooth muscle cells of the rat ileum. 2. After exposure to a Ca(2+)-free solution, application of Ca2+ caused a small contraction and a rise in [Ca2+]i, both of which were potentiated when the muscle was challenged with carbachol or caffeine before the addition of Ca2+. 3. Cyclopiazonic acid (CPA), a specific inhibitor of sarcoplasmic reticulum Ca(2+)-ATPase, dose-dependently decreased tension development and the rises in [Ca2+]i induced by carbachol and caffeine in the Ca(2+)-free solution, but conversely increased the Ca(2+)-induced responses even in the presence of the voltage-dependent Ca2+ channel blockers, methoxyverapamil and nifedipine. 4. The contraction and rise in [Ca2+]i evoked by Ca2+ gradually declined with time after removal of CPA, while the reverse was the case for the responses to carbachol and caffeine. 5. The Ca(2+)-induced contraction and rise in [Ca2+]i in the presence of CPA were inhibited by the replacement of Na+ with K+ or Cs+, and by the addition of Cd2+, Ba2+, Ni2+ or La3+. 6. The influx of Mn2+ was much greater in extent in the presence of CPA than in its absence. 7. These results suggest that the emptying of intracellular Ca2+ stores may activate Ca2+ influx not associated with voltage-dependent Ca2+ channels in the rat ileal smooth muscle. |
| Databáze: | OpenAIRE |
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