However, both a single bout of exercise and physical training mobilizes vasodilator prostanoids to participate with NO in a redundant fashion [26] in the Ang II responses in femoral veins are modulated. Assuming that the Ang II responses

in the femoral vein must be constantly modulated to avoid an uncontrolled increase in the resistance of blood flow in the body, prostanoids apparently serve as a backup mechanism during exercise [7]. Vasodilator prostaglandins have also been shown to counteract renal actions of endogenous Ang II in sodium-depleted humans when NO synthesis is inhibited [30]. Other studies suggest that, depending on the vascular territory, prostaglandins are even more important than NO in modulating the hemodynamic responses to Ang II [1], [6] and [36]. In parallel, http://www.selleckchem.com/products/gsk1120212-jtp-74057.html it was suggested that shear stress may reduce the tone of skeletal muscle venules by releasing endothelial NO and buy Nivolumab prostanoids [13]. The influence of exercise-induced shear stress upon the interaction between Ang II, NO and vasodilator prostanoids was also proposed in the rat portal vein [3]. Therefore, exercise-induced shear stress may stimulate the synthesis of vasodilator prostanoids in femoral veins,

thus resulting in reduction of Ang II responses. The participation of ET-1 in femoral vein responses to Ang II was also investigated in the present study. This approach was necessary because the involvement of ET-1 in exercise-induced modifications of Ang II responses was previously proposed in the rat portal vein [3]. Moreover, it Phenylethanolamine N-methyltransferase has been reported that Ang II induces the release of ET-1 in rat aorta which, in turn, modulates the contractile responses of this vascular bed to Ang II [28]. Thus, in the present study, the difference in Ang II responses observed between groups in the presence of L-NAME was suppressed by co-treatment with BQ-123. This occurred in part because the Ang II responses in preparations taken from resting-sedentary animals were attenuated in the presence of BQ-123. Therefore, in animals not exposed to exercise, Ang II appears to induce the release of ET-1 in

femoral veins, which enhances the response of Ang II through the activation of ETA. On the other hand, the presence of BQ-123 also increased Ang II responses in preparations taken from exercised-sedentary, resting-trained and exercised-trained animals, suppressing the difference observed in the presence of L-NAME only. These data indicate that, in femoral veins taken from animals subjected to acute or repeated exercise, Ang II promotes release of ET-1 and this, in turn, releases vasodilator substances through ETA, thereby attenuating the Ang II responses. These vasodilator substances are most likely vasodilator prostanoids because BQ-123 failed to reduce Ang II responses when indomethacin was added to the organ bath.