Differential regulation of nitric oxide synthase isoforms in experimental acute chagasic cardiomyopathy.
We have previously demonstrated induction and high level expression of IL-1beta, IL-6 and tumour necrosis factor-alpha in the myocardium during the acute stage of experimental Trypanosoma cruzi infection (Chagas' disease). The myocardial depressive effects of these cytokines are mediated in part by the induction of nitric oxide synthase (NOS), production of nitric oxide (NO) and formation of peroxynitrite. In this study we investigated the expression, activity and localization of NOS isoforms, and the levels of NO, malondialdehyde (a measure of oxidative stress), and peroxynitrite in rats at 1.5, 5, 10 and 15 days after infection with T. cruzi trypomastigotes. The myocardial inflammatory infiltrate and number of amastigote nests increased over the course of infection. A significant increase in tissue nitrate + nitrite levels, NOS2 mRNA, and NOS2 enzyme activity was observed at all time points in the infected compared with uninfected animals. The enzyme activity of constitutive NOS, tissue malondialdehyde levels, and NOS3 mRNA levels was only transiently increased after infection. The protein levels of the NOS isoforms paralleled their mRNA expression. While no positive nitrotyrosine immunoreactivity was detected in control myocardium, its levels increased in infected animals over time. Thus, by 1.5 days post-infection, when no parasite or immune cell infiltration could be detected, the myocardium expressed high levels of NOS and NO metabolites. Nevertheless, the early production of NO in the myocardium was not sufficient to clear the parasites.
Chandrasekar
B
B
Medical Service, Department of Veterans Affairs Medical Center, and Departments of Medicine and Pathology, The University of Texas Health Science Center, San Antonio, TX 78229-3900, USA.
Melby
P C
PC
Troyer
D A
DA
Freeman
G L
GL
D000208:Acute Disease; D000818:Animals; D002598:Chagas Cardiomyopathy / Q000201:enzymology* / Q000473:pathology; D004195:Disease Models, Animal; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D009206:Myocardium / Q000201:enzymology / Q000473:pathology; D009566:Nitrates / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D009573:Nitrites / Q000378:metabolism; D012333:RNA, Messenger; D051381:Rats; D011917:Rats, Inbred Lew
D007527:Isoenzymes; D009566:Nitrates; D009573:Nitrites; D012333:RNA, Messenger; C039642:peroxynitric acid; D008315:Malondialdehyde; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496322:Nos1 protein, rat; C496318:Nos2 protein, rat; C496316:Nos3 protein, rat