title: Ovine adrenal fasciculata cells contain angiotensin-II receptors coupled to intracellular effectors but are resistant to the steroidogenic effects of this hormone.
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.
authors.affiliation: INSERM U 307, Hôpital Debrousse, Lyon, France.
authors.forename: I
authors.initials: I
authors.lastname: Viard
authors.forename: W E
authors.initials: WE
authors.lastname: Rainey
authors.forename: A M
authors.initials: AM
authors.lastname: Capponi
authors.forename: M
authors.initials: M
authors.lastname: Begeot
authors.forename: J M
authors.initials: JM
authors.lastname: Saez
mesh_terms: D000311:Adrenal Glands / Q000166:cytology / Q000378:metabolism*; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D004789:Enzyme Activation; D007295:Inositol Phosphates / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D009994:Osmolar Concentration; D011493:Protein Kinase C / Q000378:metabolism; D011945:Receptors, Angiotensin / Q000378:metabolism*; D012756:Sheep; D013256:Steroids / Q000096:biosynthesis*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D007295:Inositol Phosphates; D011945:Receptors, Angiotensin; D013256:Steroids; D000804:Angiotensin II; D000324:Adrenocorticotropic Hormone; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium