Inositol 1,4,5-trisphosphate formation and ryanodine-sensitive oscillations of cytosolic free Ca2+ concentrations in neuroblastoma x fibroblast hybrid NL308 cells expressing m2 and m4 muscarinic acetylcholine receptor subtypes
| Autor: | Mami Noda, Haruhiro Higashida, David Brown, Yasuhiro Kimura, Nobuto Ishizaka, Minako Hashii, Morio Katayama, Kazuhiko Fukuda |
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| Rok vydání: | 1995 |
| Předmět: |
medicine.medical_specialty
Physiology Clinical Biochemistry Inositol 1 4 5-Trisphosphate Biology Hybrid Cells Transfection chemistry.chemical_compound Mice Neuroblastoma Radioligand Assay Cytosol Physiology (medical) Internal medicine Muscarinic acetylcholine receptor medicine Extracellular Animals Inositol Fluorometry Virulence Factors Bordetella Egtazic Acid Ryanodine receptor Ryanodine Muscarinic acetylcholine receptor M3 Fibroblasts Molecular biology Receptors Muscarinic Acetylcholine EGTA Endocrinology chemistry Pertussis Toxin Type C Phospholipases Second messenger system Calcium Fura-2 medicine.drug |
| Zdroj: | Pflugers Archiv : European journal of physiology. 429(3) |
| ISSN: | 0031-6768 |
| Popis: | Intracellular free Ca2+ concentrations ([Ca2+]i) were measured in subclones of NL308 neuroblastoma x fibroblast hybrid cells expressing each of the individual muscarinic acetylcholine receptor (mAChR) subtypes m1, m2, m3 and m4. Application of 100 μM acetylcholine (ACh) increased [Ca2+]i in all four subclones. The increased [Ca2+]i levels were significantly higher in m1- and m3-transformed cells than those in m2- and m4-transformed cells. In more than 95% of m2- and m4-transformed cells, [Ca2+]i showed sinusoidal oscillations. ACh-induced increases in [Ca2+]i were not observed in cells treated with an intracellular Ca2+ chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N∼'-tetraacetic acid (BAPTA). Removal of extracellular Ca2+ with ethyleneglycol-bis-(β-aminoethyl)-N,N,N′,N∼'-tetraacetate (EGTA) did not affect the initial [Ca2+]i increases, but reduced the late phases of Δ[Ca2+]i in m1- and m3-transformed cells by 20–30%. Oscillations in m2- and m4-transformed cells persisted in EGTA solution (though sometimes slowed in frequency), suggesting that they were of intracellular origin. ACh-induced Δ [Ca2+]i and inositol 1,4,5-trisphosphate formation was completely suppressed by pre-treatment with 50–100 ng ml−1 Pertussis toxin (PTX) for 12 h in m2- and m4-transformed cells, but not in m1 and m3-transformed cells. In all cells, extracellular application of caffeine and ryanodine, or intracellular application of cyclic adenosine diphosphate ribose (cADPR) produced a rise in [Ca2+]i. ACh-induced [Ca2+]i oscillations were not observed in ryanodine-treated m2-transformed cells. These results show that, while all four mAChRs utilize Ca2+ as a common second messenger, m2 and m4 receptors use a different signalling pathway to that used by m1 and m3 receptors. |
| Databáze: | OpenAIRE |
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