Ovine adrenal fasciculata cells contain angiotensin-II receptors coupled to intracellular effectors but are resistant to the steroidogenic effects of this hormone

Endocrinology. 1990 Nov;127(5):2071-8. doi: 10.1210/endo-127-5-2071.

Abstract

Ovine adrenal fasciculata cells (OAC) responded to ACTH but were resistant to the steroidogenic action of angiotensin-II (A-II), while bovine adrenal fasciculata cells (BAC) responded to this hormone as well as to ACTH. However both cell types contained specific A-II binding sites (120,000 +/- 14,000 and 85,000 +/- 10,000 sites per cell for OAC and BAC, respectively) of similar high affinity [dissociation constant (KD) congruent to 2 x 10(-9) M]. Moreover, in both cell types, A-II receptors were coupled to intracellular effectors since A-II: 1) stimulated the accumulation of inositol phosphates, although the effects in BAC were higher than in OAC; 2) enhanced the influx and the efflux of 45Ca2+; 3) increased cytosolic free Ca2+ concentration ([Ca2+]i); 4) potentiated ACTH-induced cAMP production; and 5) induced A-II receptor loss. Both cell types appear to have an active protein kinase C since the phorbol ester 4 beta-phorbol 12-myristate-13-acetate potentiates ACTH-induced cAMP production and caused A-II receptor loss. In addition, 4 beta-phorbol 12-myristate-13-acetate and Ca2+ ionophore enhanced the steroid production by BAC but had no effect on OAC. These results indicated that the steroidogenic refractoriness of OAC to A-II might involve some step(s) beyond the initial activation of the two branches of the phosphoinositide pathway, activation of protein kinase C and increase of [Ca2+]i, and before conversion of cholesterol to pregnenolone.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adrenal Glands / cytology
  • Adrenal Glands / metabolism*
  • Adrenocorticotropic Hormone / pharmacology
  • Angiotensin II / pharmacology*
  • Animals
  • Calcium / metabolism
  • Cattle
  • Cells, Cultured
  • Enzyme Activation
  • Inositol Phosphates / metabolism
  • Intracellular Membranes / metabolism
  • Osmolar Concentration
  • Protein Kinase C / metabolism
  • Receptors, Angiotensin / metabolism*
  • Sheep
  • Steroids / biosynthesis*
  • Tetradecanoylphorbol Acetate / pharmacology

Substances

  • Inositol Phosphates
  • Receptors, Angiotensin
  • Steroids
  • Angiotensin II
  • Adrenocorticotropic Hormone
  • Protein Kinase C
  • Tetradecanoylphorbol Acetate
  • Calcium