. Activation of Rho/Rho kinase signaling pathway by reactive oxygen species in rat aorta. Am J Physiol Heart Circ Physiol 287: H1495-H1500; 2004; 10.1152/ajpheart.01006.2003.-Evidence indicates that both the Rho/ Rho kinase signaling pathway and reactive oxygen species (ROS) such as superoxide and H 2O2 are involved in the pathogenesis of hypertension. This study aimed to determine whether ROS-induced vascular contraction is mediated through activation of Rho/Rho kinase. Rat aortic rings (endothelium denuded) were isolated and placed in organ chambers for measurement of isometric force development. ROS were generated by a xanthine (X)-xanthine oxidase (XO) mixture. The antioxidants tempol (3 mM) and catalase (1,200 U/ml) or the XO inhibitor allopurinol (400 M) significantly reduced X/XOinduced contraction. A Rho kinase inhibitor, (ϩ)-(R)-trans-4-(1-aminoethyl-N-4-pyridil)cyclohexanecarboxamide dihydrochloride (Y-27632), decreased the contraction in a concentration-dependent manner; however, the Ca 2ϩ -independent protein kinase C inhibitor rottlerin did not have an effect on X/XO-induced contraction. Phosphorylation of the myosin light chain phosphatase target subunit (MYPT1) was increased by ROS, and preincubation with Y-27632 blocked this increased phosphorylation. Western blotting for cytosolic and membrane-bound fractions of Rho showed that Rho was increased in the membrane fraction by ROS, suggesting activation of Rho. These observations demonstrate that ROS-induced Ca 2ϩ sensitization is through activation of Rho and a subsequent increase in Rho kinase activity but not Ca 2ϩ -independent PKC. myosin light chain phosphatase; smooth muscle contraction; antioxidants CONTRACTION OF SMOOTH MUSCLE is regulated by both Ca 2ϩ -dependent and Ca 2ϩ -independent (Ca 2ϩ sensitization) mechanisms. A rise in intracellular Ca 2ϩ levels leads to myosin light chain (MLC) kinase activation, resulting in an increase in MLC phosphorylation. Importantly, MLC phosphorylation can also be increased through inhibition of MLC phosphatase, which augments smooth muscle force generation without a change in intracellular Ca 2ϩ (38).In recent years, studies have revealed that the small GTPase Rho and its downstream target Rho kinase mediate the Ca 2ϩ sensitization of smooth muscle contraction (37). The exchange of bound GDP for GTP activates Rho and stimulates its translocation from cytosol to membrane. Rho-GTP phosphorylates Rho kinase, which inhibits MLC phosphatase activity by phosphorylation of the MLC phosphatase target subunit (MYPT1). A decrease in MLC phosphatase activity increases phosphorylation of myosin and therefore contributes to smooth muscle contraction at low levels of intracellular Ca 2ϩ concentration. Strong evidence suggests that increased Rho/Rho kinase-dependent Ca 2ϩ sensitization contributes to hypertension and inhibition of Rho or Rho kinase reduces blood pressure (33, 42). Some heterotrimetric G protein-coupled receptor (GPCR) agonists, including angiotensin II (ANG II) and endothelin (ET)-1, induce smooth mus...

This review summarizes the progress of pre-lithiation technologies involving the fundamental research and practical application of LICs.

Introduction Hypertension is a risk factor for erectile dysfunction (ED). The pathophysiologic basis of ED in hypertension remains largely unknown. Aim The goal of this study was to test the hypothesis that increased nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity contributes to the development of hypertension-associated ED. Methods Male Sprague-Dawley rats were implanted with osmotic pumps containing saline or angiotensin II (Ang II, 70 ng/min) for 28 days and treated with or without the NADPH oxidase inhibitor apocynin (10 mM) in the drinking water. Main Outcome Measures Erectile function was examined by measuring the mean arterial blood pressure (MAP) and intracavernosal pressure (ICP) upon electrical stimulation of the cavernous nerve. Protein expression levels of NADPH oxidase subunits were analyzed by Western blot. Reactive oxygen species production was determined by dihydroethidium (DHE) staining and thiobarbituric acid reactive substances (TBARS) assay. Results Maximum ICP (MaxICP) and ICP area under the curve, which were normalized by MAP, were significantly reduced in Ang II-infused hypertensive rats compared to that of normotensive rats (P <0.05). Protein expression of NADPH oxidase subunit p47phox was significantly increased by 30% in Ang II-infused hypertensive rat penes along with increased DHE staining and TBARS levels (P <0.05) when compared to that of controls. There were no significant changes in p67phox or gp91phox protein expression. Apocynin reduced NADPH oxidase protein expression and TBARS levels as well as improved MaxICP and ICP area under curve in Ang II-infused hypertensive rats (P <0.05). Conclusions These data suggest that activation of NADPH oxidase is a molecular mechanism for hypertension-associated ED. Apocynin treatment exerted protective effects on erectile function through inhibition of NADPH oxidase activity, thereby reducing oxidative stress in Ang II-infused hypertensive rats. This is the first study to identify the importance of NADPH oxidase in the regulation of erectile function in vivo.