15-Hydroxyeicosatetraenoic acid (15-HETE), one of many important metabolic products of arachidonic acid (AA) catalyzed by 15-lipoxygenase, plays an important role in pulmonary vascular smooth muscle remodeling. We have previously shown its unsubstituted effects on the apoptotic responses of pulmonary artery smooth muscle cells (PASMCs), but the underlying mechanisms are still poorly manifested. Previous studies have shown that inducible nitric oxide synthase (iNOS) plays an important protective role against sepsis-induced pulmonary apoptosis. Therefore, the purpose of this study is to determine whether 15-HETE anti-apoptotic process is mediated through the iNOS pathway in rat PASMCs. To test this hypothesis, we studied the contribution of iNOS to the 15-HETE induced anti-apoptotic responses using cell viability measurement, Western blot, mitochondrial potential analysis, nuclear morphology determination and TUNEL assay. Our results showed that both exogenous and endogenous 15-HETE up-regulated iNOS protein and mRNA expression and 15-HETE enhanced the cell survival, attenuated mitochondrial depolarization, up-regulated the expression of Bcl-2 and procaspase-3 in PASMCs under serum-deprived condition. These effects were reversed by iNOS inhibitor SMT or l-canavanine. Taken together, our data indicates that iNOS is a novel signaling transduction pathway, which is necessary for the effects of 15-HETE in protection PASMCs from apoptosis and may be an important mechanism underlying the treatment of pulmonary artery hypertension and also provides a novel therapeutic insight in future.
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