The lifetime of inositol 1,4,5-trisphosphate in single cells
| Autor: | Stuart H. Thompson, Adawia A. Alousi, Samuel S.-H. Wang |
|---|---|
| Rok vydání: | 1995 |
| Předmět: |
inorganic chemicals
endocrine system medicine.medical_specialty Carbachol Fura-2 Physiology chemistry.chemical_element Calcium-Transporting ATPases Inositol 1 4 5-Trisphosphate Calcium Muscarinic agonist Feedback Mice Neuroblastoma chemistry.chemical_compound Internal medicine Tumor Cells Cultured medicine Animals Inositol Receptor Egtazic Acid Calcium metabolism Half-life Cell Differentiation Articles carbohydrates (lipids) Kinetics Eukaryotic Cells Endocrinology chemistry Biophysics Half-Life medicine.drug |
| Zdroj: | The Journal of General Physiology |
| ISSN: | 1540-7748 0022-1295 |
| DOI: | 10.1085/jgp.105.1.149 |
| Popis: | In many eukaryotic cell types, receptor activation leads to the formation of inositol 1,4,5-trisphosphate (IP3) which causes calcium ions (Ca) to be released from internal stores. Ca release was observed in response to the muscarinic agonist carbachol by fura-2 imaging of N1E-115 neuroblastoma cells. Ca release followed receptor activation after a latency of 0.4 to 20 s. Latency was not caused by Ca feedback on IP3 receptors, but rather by IP3 accumulation to a threshold for release. The dependence of latency on carbachol dose was fitted to a model in which IP3 synthesis and degradation compete, resulting in gradual accumulation to a threshold level at which Ca release becomes regenerative. This analysis gave degradation rate constants of IP3 in single cells ranging from 0 to 0.284 s-1 (0.058 +/- 0.067 s-1 SD, 53 cells) and a mean IP3 lifetime of 9.2 +/- 2.2 s. IP3 degradation was also measured directly with biochemical methods. This gave a half life of 9 +/- 2 s. The rate of IP3 degradation sets the time frame over which IP3 accumulations are integrated as input signals. IP3 levels are also filtered over time, and on average, large-amplitude oscillations in IP3 in these cells cannot occur with period < 10 s. |
| Databáze: | OpenAIRE |
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