Dataset Information

H.p.l.c. analysis of inositol monophosphate isomers formed on angiotensin II stimulation of rat adrenal glomerulosa cells.

ABSTRACT: [3H]Inositol-prelabelled isolated rat adrenal glomerulosa cells were stimulated with 25 nM-AII ([Asp1, Ile5]-angiotensin II) in the presence of 10 mM-Li+, and the resulting inositol monophosphate isomers were separated successfully by using a recently developed h.p.l.c. methodology. Two major peaks of radioactivity were detected which showed the same retention characteristics on h.p.l.c. as inositol 4-phosphate and inositol 1-phosphate and which increased 5-fold and 8-fold respectively on stimulation with AII. In addition, a relatively small peak with the retention characteristics of inositol 1:2-cyclic phosphate was seen to undergo a 1.5-fold increase on stimulation. This was not considered sufficient to suggest that cyclic phosphoinositols were a major product of AII-stimulated phosphoinositide turnover. No peaks of radioactive material were detected in the regions expected for inositol 2-phosphate (an acid hydrolysis product of inositol 1:2-cyclic phosphate) or inositol 5-phosphate. These results establish the identity of the major inositol phosphate products in AII-stimulated glomerulosa cells and confirm and extend the previous observations of Balla, Baukal, Guillemette, Morgan & Catt [(1986) Proc. Natl. Acad. Sci. 83, 9323-9327].

SUBMITTER: Bird IM

PROVIDER: S-EPMC1148519 | biostudies-other | 1987 Nov

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:Angiotensin II (AngII) plays a crucial role in the control of aldosterone biosynthesis in adrenal glomerulosa cells through the stimulation of two distinct Ca2+ entry pathways: (1) opening of voltage-operated calcium channels, and (2) activation of a capacitative Ca2+ entry that is dependent on calcium release from intracellular pools. Adrenocorticotrophic hormone (ACTH), on the other hand, a major hormonal regulator of steroidogenesis, induces an increase in intracellular cAMP through the activation of a G-protein-coupled adenylyl cyclase. Recent studies have demonstrated that the rise in cAMP induced by ACTH can be potentiated by AngII in bovine glomerulosa cells. The aim of the present study was to investigate the mechanism of AngII action on ACTH-induced cAMP production. In primary cultures of bovine glomerulosa cells, we found that AngII (100 nM), which had no effect by itself on cAMP production, significantly potentiated maximal ACTH-induced cAMP formation in the presence of extracellular calcium (1.2 mM). In contrast, in the absence of extracellular calcium, AngII did not affect ACTH-induced cAMP production. These results suggest that calcium entry into the cell plays an important role in the activation of the cyclase by AngII. The inhibition of voltage-operated calcium channels by nicardipine, a dihydropyridine calcium antagonist blocking both low-threshold (T-type) and high-threshold (L-type) Ca2+ channels, did not significantly affect the potentiating effect of AngII. Moreover, the cAMP response to ACTH was insensitive to activation of these Ca2+ channels induced by potassium ions and, even when cytosolic free-calcium concentration ([Ca2+]c) was kept elevated with the Ca2+ ionophore, ionomycin, no stimulation of adenylyl cyclase was observed at concentrations of [Ca2+]c up to 640 nM. In contrast, thapsigargin, an activator of capacitative Ca2+ influx, mimicked the potentiating effect of AngII on ACTH-induced cAMP formation. In agreement with the characteristics of cAMP modulation by Ca2+ in these cells, the presence of type III adenylyl cyclase was observed by immunodetection in bovine glomerulosa cell membranes. In conclusion, these data suggest a tight coupling between the capacitative Ca2+ influx induced upon stimulation by either AngII or thapsigargin and a calcium-sensitive isoform of adenylyl cyclase, probably type III, in bovine glomerulosa cells.

Dataset Information

H.p.l.c. analysis of inositol monophosphate isomers formed on angiotensin II stimulation of rat adrenal glomerulosa cells.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets