Angiotensin II causes calcium entry into bovine adrenal chromaffin cells via pathway(s) activated by depletion of intracellular calcium stores.
The characteristics and properties of the increase in cytosolic [Ca2+] that occurs in bovine adrenal medullary chromaffin cells on exposure to angiotensin 11 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.
Powis
David A
DA
School of Biomedical Sciences, Faculty of Health, The University of Newcastle, New South Wales, 2308, Australia.
Zerbes
Mariann
M
Herd
Lynn M
LM
Dunkley
Peter R
PR
D000311:Adrenal Glands / Q000166:cytology; D000804:Angiotensin II / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002417:Cattle; D002478:Cells, Cultured; D019284:Thapsigargin / Q000494:pharmacology
D000804:Angiotensin II; D019284:Thapsigargin; D000252:Calcium-Transporting ATPases; D002118:Calcium