Angiotensin II causes calcium entry into bovine adrenal chromaffin cells via pathway(s) activated by depletion of intracellular calcium stores |
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Authors: | Powis David A Zerbes Mariann Herd Lynn M Dunkley Peter R |
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Institution: | (1) School of Biomedical Sciences, Faculty of Health, The University of Newcastle, New South Wales, 2308, Australia |
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Abstract: | The characteristics and properties of the increase in cytosolic Ca2+] that occurs in bovine adrenal medullary chromaffin cells on exposure to angiotensin II have been investigated. In fura-2 loaded cells exposure to a maximally effective concentration of angiotensin II (100 nM) caused a rapid, but transient increase in cytosolic Ca2+] followed by a lower plateau that was sustained as long as external Ca2+ was present. In the absence of external Ca2+ only the initial brief transient was observed. In cells previously treated with thapsigargin in Ca2+-free medium to deplete the internal Ca2+ stores, angiotensin II caused no increase in cytosolic Ca2+] when external Ca2+ was absent. Reintroduction of external Ca2+ to thapsigargin-treated, store-depleted cells caused a sustained increase in cytosolic Ca2+] that was not further increased upon exposure to angiotensin II. Analysis of the data suggests that in bovine chromaffin cells angiotensin II causes Ca2+ entry via a pathway(s) activated as a consequence of internal store mobilization, and entry through this pathway(s) forms the majority of the sustained Ca2+ influx evoked by angiotensin II. |
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Keywords: | Bovine chromaffin cells angiotensin II Ca2+ entry pathways intracellular Ca2+ stores |
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