The relationship of ventricular dynamics and mitochondrial nitric oxide synthase activity in septic shock models

The aim of the present study was to investigate the role of mitochondrial nitric oxide synthase (mtNOS) in the septic shock and analyze its relationship to ventricular contractility. Two models of septic shock [lipopolysaccharide (LPS)-induced and cecal ligation and puncture (CLP)-induced] were used. There was a significant depression of ventricular contractile parameters recorded in the late stage of the septic shock. After measurement of ventricular-dynamic parameters, mitochondrial and cytoplasmic fractions were isolated and their nitric oxide synthase (NOS) activity was assessed using a NOS activity assay kit. Both models showed a larger increase in mitochondrial NOS activity than that in cytosol. However, the increase in mtNOS activity in the LPS-induced shock model was less pronounced than in the CLP-induced model. Regression analysis shows that mitochondrial nitric oxide synthase (mtNOS) activity is negatively correlative to the left ventricular developed pressure in CLP model. The results suggest that mitochondrial NOS may mainly contribute to the ventricular depression in the septic shock.