AT(1) receptor activation regulates the mRNA expression of CAT1, CAT2, arginase-1, and DDAH2 in preglomerular vessels from angiotensin II hypertensive rats.
Previously, we found increased expression of l-arginine metabolizing enzymes in both kidneys from two-kidney, one-clip (2K1C) hypertensive rats (Helle F, Hultstrom M, Skogstrand T, Palm F, Iversen BM. Am J Physiol Renal Physiol 296: F78-F86, 2009). In the present study, we investigate whether AT(1) receptor activation can induce the changes observed in 2K1C. Four groups of rats were infused with 80 ng/min ANG II or saline for 14 days and/or given 60 mg x kg(-1) x day(-1) losartan. Gene expression was studied in isolated preglomerular vessels by RT-PCR. Dose-responses to ANG II were studied in isolated preglomerular vessels with and without acute NOS inhibition [10(-4) mol/l N(G)-nitro-l-arginine methyl ester (l-NAME)]. Expressions of endothelial nitric oxide synthase (eNOS), caveolin-1, and arginase-2 were not changed by ANG II infusion. CAT1 (0.3 8 +/- 0.07 to 0.73 +/- 0.12, P < 0.05), CAT2 (1.14 +/- 0.29 to 2.74 +/- 0.48), DDAH2 (1.09 +/- 0.27 to 2.3 +/- 0.46), and arginase-1 (1.08 +/- 0.17 to 1.82 +/- 0.22) were increased in ANG II-infused rats. This was prevented by losartan treatment, which reduced the expression of eNOS (0.97 +/- 0.26 to 0.37 +/- 0.11 in controls; 0.8 +/- 0.16 to 0.36 +/- 0.1 in ANG II-infused rats) and caveolin-1 (2.49 +/- 0.59 to 0.82 +/- 0.24 in controls and 2.59 +/- 0.61 to 1.1 +/- 0.25 in ANG II-infused rats). ANG II (10(-10) mol/l) caused vessels from ANG II-infused animals to contract to 53 +/- 15% of baseline diameter and 90 +/- 5% of baseline diameter in controls (P < 0.05) and was further enhanced by l-NAME to 4 +/- 4% of baseline diameter (P < 0.05). In vivo losartan treatment reduced the reactivity of isolated vessels to 91 +/- 2% of baseline in response to 10(-7) mol/l ANG II compared with 82 +/- 3% in controls (P < 0.05) and prevented the increased responsiveness caused by ANG II infusion. In conclusion, CAT1, CAT2, DDAH2, and arginase-1 expression in renal resistance vessels is regulated through the AT(1) receptor. This finding may be of direct importance for NOS and the regulation of preglomerular vascular function.
Hultström
Michael
M
Renal Research Group, Department of Internal Medicine, Haukeland University Hospital, 5021 Bergen, Norway. michael.hultstrom@med.uib.no
Helle
Frank
F
Iversen
Bjarne M
BM
D000581:Amidohydrolases / Q000235:genetics / Q000378:metabolism*; D000804:Angiotensin II / Q000494:pharmacology; D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology; D000818:Animals; D001119:Arginase / Q000235:genetics / Q000378:metabolism*; D001160:Arterioles / Q000378:metabolism* / Q000473:pathology; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D006973:Hypertension / Q000378:metabolism* / Q000473:pathology; D007678:Kidney Glomerulus / Q000098:blood supply*; D019808:Losartan / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D044140:Receptor, Angiotensin, Type 1 / Q000187:drug effects / Q000378:metabolism*; D050916:TRPV Cation Channels / Q000235:genetics / Q000378:metabolism*
D047228:Angiotensin II Type 1 Receptor Blockers; D015220:Calcium Channels; D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D050916:TRPV Cation Channels; C492241:TRPV5 protein, rat; C120776:TRPV6 channel; D000804:Angiotensin II; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D000581:Amidohydrolases; D001119:Arginase; C059999:dimethylargininase; D019808:Losartan