-
Views
-
Cite
Cite
I. VIARD, W. E. RAINEY, A. M. CAPPONI, M. BEGEOT, J. M. SAEZ, Ovine Adrenal Fasciculata Cells Contain Angiotensin-II Receptors Coupled to Intracellular Effectors but Are Resistant to the Steroidogenic Effects of This Hormone, Endocrinology, Volume 127, Issue 5, 1 November 1990, Pages 2071–2078, https://doi.org/10.1210/endo-127-5-2071
Close - Share Icon Share
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) = 2 × 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 4β-phorbol 12- myristate-13-acetate potentiates ACTH-induced cAMP production and caused A-II receptor loss. In addition, 4β-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. (Endocrinology127: 2071–2078, 1990)
