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Angiotensin II negatively modulates L-type calcium channels through a pertussis toxin-sensitive G protein in adrenal glomerulosa cells

Published in The Journal of biological chemistry. 1999, vol. 274, no. 28, p. 19943-8
Abstract In bovine adrenal glomerulosa cells, angiotensin II and extracellular K+ stimulate aldosterone secretion in a calcium-dependent manner. In these cells, physiological concentrations of extracellular potassium activate both T-type (low threshold) and L-type (high threshold) voltage-operated calcium channels. Paradoxically, the cytosolic calcium response to 9 mM K+ is inhibited by angiotensin II. Because K+-induced calcium changes observed in the cytosol are almost exclusively due to L-type channel activity, we therefore studied the mechanisms of L-type channel regulation by angiotensin II. Using the patch-clamp method in its perforated patch configuration, we observed a marked inhibition (by 63%) of L-type barium currents in response to angiotensin II. This effect of the hormone was completely prevented by losartan, a specific antagonist of the AT1 receptor subtype. Moreover, this inhibition was strongly reduced when the cells were previously treated for 1 night with pertussis toxin. An effect of pertussis toxin was also observed on the modulation by angiotensin II of the K+ (9 mM)-induced cytosolic calcium response in fura-2-loaded cells, as well as on the angiotensin II-induced aldosterone secretion, at both low (3 mM) and high (9 mM) K+ concentrations. Finally, the expression of both Go and Gi proteins in bovine glomerulosa cells was detected by immunoblotting. Altogether, these results strongly suggest that in bovine glomerulosa cells, a pertussis toxin-sensitive G protein is involved in the inhibition of L-type channel activity induced by angiotensin II.
Keywords Aldosterone/metabolismAngiotensin II/metabolismAnimalsCalcium/metabolismCalcium Channels/metabolismCalcium Channels, L-TypeCattleCells, CulturedGTP-Binding Proteins/metabolismLosartan/pharmacologyPatch-Clamp TechniquesPertussis ToxinPotassium/pharmacologyVirulence Factors, Bordetella/pharmacologyZona Glomerulosa
PMID: 10391942
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Research group Signaux intracellulaires (210)
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MATURANA, Andrés et al. Angiotensin II negatively modulates L-type calcium channels through a pertussis toxin-sensitive G protein in adrenal glomerulosa cells. In: The Journal of biological chemistry, 1999, vol. 274, n° 28, p. 19943-8. doi: 10.1074/jbc.274.28.19943 https://archive-ouverte.unige.ch/unige:30337

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Deposited on : 2013-10-11

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