The role of alpha1 (connexin-43) gap junction expression in adrenal cortical cell function

To investigate the relationship between adrenal cell function and gap junction expression, a bovine adrenal cell line (SBAC) was studied. Western blot and immunocytochemical techniques were used to demonstrate gap junction expression in SBAC cell populations. Cells expressed alpha1 (connexin 43) gap junction protein at points of cell-to-cell contact. Gap junction number and size increased in populations treated with ACTH (40 mU/ml) or dibutyryl cAMP (DbcAMP, 1.0 mM). Treatment with either ACTH or DbcAMP increased steroid production and cAMP levels. SBAC cell number, however, decreased in ACTH- or DbcAMP-treated populations. The number of cells increased in cultures transfected with alpha1-antisense complementary DNA. Neither ACTH nor DbcAMP treatment decreased cell number or increased steroidogenesis in alpha1-antisense complementary DNA-transfected cell populations. However, cell populations in which gap junctions were inhibited retained the capacity to increase cAMP production in response to ACTH (40 mU/ml) treatment. Hormone-stimulated gapjunction expression and cell communication may represent an important factor in adrenal gland function and control of proliferation.