Transgenic expression of human-like iPLA2beta in mice subjected to cardiac ischemia increased fatty acid release (29.4 vs 1.35 nmol/ml) and precipitated malignant ventricular tachyarrhythmias.
Does iPLA2beta activation during cardiac ischemia precipitate ventricular tachyarrhythmias in a transgenic mouse model?
Activation of iPLA2beta during acute cardiac ischemia mediates membrane phospholipid hydrolysis and precipitates lethal ventricular tachyarrhythmias in a humanized mouse model.
Tasa de eventos absoluta: 29.4% vs 1.35%
Murine myocardium contains diminutive amounts of calcium-independent phospholipase A2 (iPLA2) activity (<5% that of human heart), and malignant ventricular tachyarrhythmias are infrequent during acute murine myocardial ischemia. Accordingly we considered the possibility that the mouse was a species-specific knockdown of the human pathologic phenotype of ischemiainduced lethal ventricular tachyarrhythmias. Transgenic mice were generated expressing amounts of iPLA2beta activity comparable to that present in human myocardium. Coronary artery occlusion in Langendorff perfused hearts from transgenic mice resulted in a 22-fold increase in fatty acids released into the venous eluent (29.4 nmol/ml in transgenic versus 1.35 nmol/ml of eluent in wild-type mice), a 4-fold increase in lysophosphatidylcholine mass in ischemic zones (4.9 nmol/mg in transgenic versus 1.1 nmol/mg of protein in wild-type mice), and malignant ventricular tachyarrhythmias within minutes of ischemia. Neither normally perfused transgenic nor ischemic wild-type hearts demonstrated these alterations. Pretreatment of Langendorff perfused transgenic hearts with the iPLA2 mechanism-based inhibitor (E)-6-(bromomethylene)-3-(1-naphthalenyl)-2H-tetrahydropyran-2-one (BEL) just minutes prior to induction of ischemia completely ablated fatty acid release and lysolipid accumulation and rescued transgenic hearts from malignant ventricular tachyarrhythmias. Collectively these results demonstrate that ischemia activates iPLA2beta in intact myocardium and that iPLA2beta-mediated hydrolysis of membrane phospholipids can induce lethal malignant ventricular tachyarrhythmias during acute cardiac ischemia.
Mancuso et al. (Sun,) conducted a other in Acute myocardial ischemia and ventricular tachyarrhythmias. Transgenic expression of iPLA2beta and coronary artery occlusion vs. Wild-type mice was evaluated on Fatty acid release into venous eluent (nmol/ml). Transgenic expression of human-like iPLA2beta in mice subjected to cardiac ischemia increased fatty acid release (29.4 vs 1.35 nmol/ml) and precipitated malignant ventricular tachyarrhythmias.
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