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

Article Article scientifique Article Angiotensin II negatively modulates L-type calcium channels through a pertussis toxin-sensitive G protein in adrenal glomerulosa cells eng 1999 author Maturana Andrés 58360 author Casal Andrés José 41599 author Demaurex Nicolas 0000-0002-9933-6772 24642 author Vallotton Michel 25057 author Capponi Alessandro Mario 24743 author Rossier Michel 22435 19943-19948 10.1074/jbc.274.28.19943 10391942 0021-9258 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. Aldosterone/metabolism Angiotensin II/metabolism Animals Calcium/metabolism Calcium Channels/metabolism Calcium Channels, L-Type Cattle Cells, Cultured GTP-Binding Proteins/metabolism Losartan/pharmacology Patch-Clamp Techniques Pertussis Toxin Potassium/pharmacology Virulence Factors, Bordetella/pharmacology Zona Glomerulosa Dewey 616 56 Département de médecine 221 false 168 Signaux intracellulaires 210 The Journal of biological chemistry 274 28 7711a429-a5cf-446e-9165-547f5d8588e8 Article (Published version) Public Angiotensin II negatively modulates L-type calcium channels through a pertussis toxin-sensitive G protein in adrenal glomerulosa cells.pdf 223276 application/pdf openAccess Faculté de médecine / Section de médecine clinique / Département de médecine

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Angiotensin II negatively modulates L-type calcium channels through a pertussis toxin-sensitive G protein in adrenal glomerulosa cells	The Journal of biological chemistry			1999	744	401

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Casal, Andrés José