Agonist-dependent patterns of cytosolic Ca2+ changes in single bovine adrenal chromaffin cells: relationship to catecholamine release

Cell Regul. 1990 Aug;1(9):683-91. doi: 10.1091/mbc.1.9.683.

Abstract

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.

MeSH terms

  • Adrenal Medulla / cytology
  • Adrenal Medulla / drug effects
  • Adrenal Medulla / metabolism*
  • Angiotensin II / pharmacology
  • Animals
  • Buffers
  • Calcium / metabolism*
  • Cattle
  • Cells, Cultured
  • Chromaffin Granules / drug effects
  • Chromaffin Granules / metabolism*
  • Cytosol / metabolism
  • Electric Conductivity
  • Histamine / pharmacology
  • Norepinephrine / metabolism*

Substances

  • Buffers
  • Angiotensin II
  • Histamine
  • Calcium
  • Norepinephrine