Angiotensin II upregulates Ca(V)1.2 protein expression in cultured arteries via endothelial H(2)O(2) production.
BACKGROUND
We previously reported that angiotensin II caused an endothelial-dependent increase in L-type voltage-dependent Ca(2+) channel (Ca(V)1.2) in cultured arteries, but the signaling pathways are not clear.


METHODS
Endothelial damage was generated by brief intra-arterial perfusion with 0.3% CHAPS. Ca(V)1.2 expression, function and H(2)O(2) were measured by Western blot, tension recording and Amplex Red H(2)O(2) assay kit, respectively.


RESULTS
Angiotensin II dose-dependently upregulated Ca(V)1.2 expression in endothelium-intact arteries. The angiotensin II upregulation of Ca(V)1.2 expression in endothelium-intact arteries was blocked by NAD(P)H oxidase inhibitor diphenyleneiodonium (DPI), apocynin, a more specific NAD(P)H oxidase inhibitor gp91ds-tat and also by catalase. H(2)O(2) similarly upregulated Ca(V)1.2 expression in endothelium-intact and endothelium-damaged arteries, and the latter effect was also blocked by DPI and apocynin. Angiotensin II increased H(2)O(2) production by endothelium-intact but not by endothelium-damaged arteries, and this effect was blocked by apocynin, catalase and gp91ds-tat. The upregulation of Ca(V)1.2 by angiotensin II and H(2)O(2) is accompanied by an increased tension response to KCl and the Ca(2+) channel activator FPL 64176, and this effect was also attenuated by gp91ds-tat.


CONCLUSIONS
These results suggest that angiotensin II stimulates endothelial NAD(P)H oxidase-produced H(2)O(2,) which may additionally act through vascular smooth muscle NAD(P)H oxidase, to upregulate vascular Ca(V)1.2 protein.
Wang
Wenze
W
Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, Ark 72205, USA. wwang @ uams.edu
Pang
Li
L
Palade
Philip
P
D000804:Angiotensin II / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D008638:Mesenteric Arteries / Q000166:cytology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology; D014662:Vasoconstrictor Agents / Q000378:metabolism / Q000494:pharmacology*
C504728:Cacna1c protein, rat; D020746:Calcium Channels, L-Type; D008562:Membrane Glycoproteins; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D006861:Hydrogen Peroxide; C500593:Cybb protein, rat; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases