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Erschienen in:
01.09.2008 | ORIGINAL CONTRIBUTION
NO and PGI2 in coronary endothelial dysfunction in transgenic mice with dilated cardiomyopathy
Erschienen in: Basic Research in Cardiology | Ausgabe 5/2008
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Objective
The aim of the present work was to analyze coronary endothelial function in the transgenic mouse model of dilated cardiomyopathy (Tgαq*44 mice).
Methods
Coronary vasodilatation, both NO-dependent (induced by bradykinin) and PGI2-dependent (induced by acetylcholine), was assessed in the isolated hearts of Tgαq*44 and FVB mice. Cardiac function was analyzed in vivo (MRI).
Results
In Tgαq*44 mice at the age of 2–4 months cardiac function was preserved and there were no alterations in endothelial function. By contrast, in Tgαq*44 mice at the age of 14–16 months cardiac function was significantly impaired and NO, but not PGI2-dependent coronary function was altered. Interestingly, the basal level of PGI2 in coronary circulation increased fourfold as compared to FVB mice. Cardiac O2
− production increased 1.5-fold and 3-fold in Tgαq*44 vs. FVB mice at the age of 2–6 and 14–16 months, respectively, and was inhibited by apocynin. Interestingly, inhibition of NADPH oxidase or NOS-3 normalized augmented PGI2 production in Tgαq*44 mice. There was also an increased expression of gp91phox in Tgαq*44 vs. FVB hearts, without evident alterations in the expression of COX-1, COX-2, NOS-3 and PGI2-synthase.
Conclusions
In the mouse model of dilated cardiomyopathy, endothelial dysfunction in coronary circulation is present in the late but not the early stage of heart failure pathology and is characterized by a decrease in NO bioavailability and a compensatory increase in PGI2. Both the decrease in NO activity and the increase in PGI2 activity may result from excessive O2
− production by cardiac NADPH oxidase in Tgαq*44 hearts.