Andrade Fernanda A, Restini Carolina B A, Grando Marcella D, Ramalho Leandra N Z, Bendhack Lusiane M
Department of Pharmacology, School of Medicine of Ribeirão Preto - University of São Paulo, São Paulo, Brasil.
Department of Medicine - University of Ribeirão Preto, Ribeirão Preto, Brasil.
PLoS One. 2014 May 1;9(5):e95446. doi: 10.1371/journal.pone.0095446. eCollection 2014.
C-type natriuretic peptide (CNP) and nitric oxide (NO) are endothelium-derived factors that play important roles in the regulation of vascular tone and arterial blood pressure. We hypothesized that NO produced by the endothelial NO-synthase (NOS-3) contributes to the relaxation induced by CNP in isolated rat aorta via activation of endothelial NPR-C receptor. Therefore, the aim of this study was to investigate the putative contribution of NO through NPR-C activation in the CNP induced relaxation in isolated conductance artery.
Concentration-effect curves for CNP were constructed in aortic rings isolated from rats. Confocal microscopy was used to analyze the cytosolic calcium mobilization induced by CNP. The phosphorylation of the residue Ser1177 of NOS was analyzed by Western blot and the expression and localization of NPR-C receptors was analyzed by immunohistochemistry.
CNP was less potent in inducing relaxation in denuded endothelium aortic rings than in intact ones. L-NAME attenuated the potency of CNP and similar results were obtained in the presence of hydroxocobalamin, an intracellular NO0 scavenger. CNP did not change the phosphorylation of Ser1177, the activation site of NOS-3, when compared with control. The addition of CNP produced an increase in [Ca2+]c in endothelial cells and a decrease in [Ca2+]c in vascular smooth muscle cells. The NPR-C-receptors are expressed in endothelial and adventitial rat aortas.
These results suggest that CNP-induced relaxation in intact aorta isolated from rats involves NO production due to [Ca2+]c increase in endothelial cells possibly through NPR-C activation expressed in these cells. The present study provides a breakthrough in the understanding of the close relationship between the vascular actions of nitric oxide and CNP.
C型利钠肽（CNP）和一氧化氮（NO）是内皮源性因子，在血管张力和动脉血压调节中发挥重要作用。我们推测内皮型一氧化氮合酶（NOS-3）产生的NO通过激活内皮NPR-C受体，有助于CNP诱导离体大鼠主动脉舒张。因此，本研究旨在探讨在离体传导动脉中，通过NPR-C激活产生的NO在CNP诱导舒张中的假定作用。
构建从大鼠分离的主动脉环中CNP的浓度-效应曲线。采用共聚焦显微镜分析CNP诱导的胞质钙动员。通过蛋白质免疫印迹分析NOS第1177位丝氨酸残基的磷酸化，通过免疫组织化学分析NPR-C受体的表达和定位。
与完整内皮的主动脉环相比，CNP诱导去内皮主动脉环舒张的效力较低。L-NAME减弱了CNP的效力，在存在细胞内NO清除剂羟钴胺素的情况下也获得了类似结果。与对照组相比，CNP未改变NOS-3激活位点第1177位丝氨酸的磷酸化。添加CNP导致内皮细胞中[Ca2+]c增加，血管平滑肌细胞中[Ca2+]c减少。NPR-C受体在大鼠主动脉的内皮和外膜中表达。
这些结果表明，从大鼠分离的完整主动脉中，CNP诱导的舒张涉及由于内皮细胞中[Ca2+]c增加可能通过这些细胞中表达的NPR-C激活而产生的NO。本研究为理解一氧化氮和CNP的血管作用之间的密切关系提供了突破。
