Angiotensin II-stimulated cortisol secretion is mediated by a hormone-sensitive phospholipase C in bovine adrenal fasciculata/reticularis cells.
Conditions have been established for the incorporation of [3H]inositol ([3H]Ins) into the phosphoinositides of cultured bovine adrenal zona fasciculata/reticularis (ZFR) cells. Stimulation of these prelabelled cells with angiotensin II (10(-11)-10(-7) M AII) resulted in the dose-dependent (max. 16-fold at 10(-7) M AII), time-dependent formation of water-soluble radiolabelled products which show the same chemical and chromatographic properties as [3H]InsP, [3H]InsP2 and [3H]InsP3 standards. The results of the time-course studies of the changes in these products are consistent with the view that AII rapidly (less than 15 s) induces the activation of a polyphosphoinositide-specific phospholipase C. The action of this phospholipase on the polyphosphoinositides is sustained throughout 15 min of stimulation. The dose dependency of this response correlates closely with cortisol output and is reduced (to 52%, P less than 0.00005), but not abolished, in the absence of extracellular Ca2+. To our knowledge these results are the first clear demonstration that AII stimulates a polyphosphoinositide-specific phospholipase C in bovine ZFR cells.
Bird
I M
IM
University Department of Biochemistry, Edinburgh, Scotland, U.K.
Meikle
I
I
Williams
B C
BC
Walker
S W
SW
D000804:Angiotensin II / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002417:Cattle; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006854:Hydrocortisone / Q000378:metabolism* / Q000502:physiology; D007294:Inositol / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D010738:Type C Phospholipases / Q000502:physiology*; D015383:Zona Fasciculata / Q000166:cytology / Q000502:physiology*; D015385:Zona Reticularis / Q000166:cytology / Q000502:physiology*
D010716:Phosphatidylinositols; D000804:Angiotensin II; D007294:Inositol; D010738:Type C Phospholipases; D002118:Calcium; D006854:Hydrocortisone