Agonist-dependent patterns of cytosolic Ca2+ changes in single bovine adrenal chromaffin cells: relationship to catecholamine release
| Autor: | M M Murawsky, K A Stauderman, R M Pruss |
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| Rok vydání: | 1990 |
| Předmět: |
Agonist
medicine.medical_specialty medicine.drug_class chemistry.chemical_element Stimulation Calcium Biology Buffers chemistry.chemical_compound Norepinephrine Cytosol Internal medicine medicine Animals Chromaffin Granules Cells Cultured Angiotensin II Electric Conductivity General Medicine Endocrinology medicine.anatomical_structure chemistry Adrenal Medulla Catecholamine Cattle Adrenal medulla Histamine Intracellular medicine.drug Research Article |
| Zdroj: | Cell regulation. 1(9) |
| ISSN: | 1044-2030 |
| Popis: | The patterns of agonist-induced elevations of cytosolic free Ca2+ ([Ca2+]i) were characterized and compared by the use of single adrenal chromaffin cells. Initial histamine- or angiotensin II (AII)-induced elevations of [Ca2+]i were equal in magnitude (peaks 329 +/- 20 [SE] and 338 +/- 46 nM, respectively). These initial increases of [Ca2+]i were transient, insensitive to either Gd3+ or removing external Ca2+, and were primarily the result of Ca2+ release from intracellular stores. After the initial peak(s) of [Ca2+]i, a second phase of moderately elevated [Ca2+]i was observed, and this response was sensitive to either Gd3+ or removing external Ca2+, supporting a role for Ca2+ entry. In most cases, the second phase of elevated [Ca2+]i was sustained during histamine stimulation but transient during AII stimulation. Maintenance of the second phase was a property of the agonist rather than of the particular cell being stimulated. Thus, individual cells exposed sequentially to histamine and AII displayed distinct patterns of [Ca2+]i changes to each agonist, regardless of the order of addition. Histamine also stimulated twice as much [3H]catecholamine release as AII, and release was completely dependent on external Ca2+. Therefore, the ability of histamine and AII to sustain (or promote) Ca2+ entry appears to underlie their efficacy as secretagogues. These data provide evidence linking agonist-dependent patterns of [Ca2+]i changes in single cells with agonist-dependent functional responses. |
| Databáze: | OpenAIRE |
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