induced obesity, namely uncoupling of the endothelial nitric oxide (NO) synthase (eNOS) in PVAT. Materials and MethodsMaterials and Methods are available in the online-only Data Supplement.© 2015 American Heart Association, Inc. Objective-The present study was conducted to investigate the contribution of perivascular adipose tissue (PVAT) to vascular dysfunction in a mouse model of diet-induced obesity. Approach and Results-Obesity was induced in male C57BL/6J mice with a high-fat diet for 20 weeks, and vascular function was studied with myograph. In PVAT-free aortas isolated from obese mice, the endothelium-dependent, nitric oxide-mediated vasodilator response to acetylcholine remained normal. In contrast, a clear reduction in the vasodilator response to acetylcholine was observed in aortas from obese mice when PVAT was left in place. Adipocytes in PVAT were clearly positive in endothelial nitric oxide synthase (eNOS) staining, and PVAT nitric oxide production was significantly reduced in obese mice. High-fat diet had no effect on eNOS expression but led to eNOS uncoupling, evidenced by diminished superoxide production in PVAT after eNOS inhibition. As mechanisms for eNOS uncoupling, arginase induction and l-arginine deficiency were observed in PVAT. Obesity-induced vascular dysfunction could be reversed by ex vivo l-arginine treatment and arginase inhibition. Conclusions-Diet-induced obesity leads to Results Role of PVAT in Vascular Dysfunction in Diet-Induced Obese MiceMale C57BL/6J mice were fed with either HFD or normal control diet (NCD) for 20 weeks starting at the age of 8 weeks.The HFD-treated mice developed obesity (Table). Vasodilator response to acetylcholine was studied using aortas with or without PVAT in a wire myograph system. In aortas without PVAT, no significant differences in endothelium-dependent, NO-mediated vasodilator response to acetylcholine were found between NCD and HFD groups ( Figure 1A). In contrast, a clear reduction in the vasodilator response to acetylcholine was observed in the aorta of obese animals compared with lean controls when PVAT was left intact ( Figure 1B). The acetylcholine-induced vasodilation in the mouse aorta was NO-dependent because it could be completely blocked by the NO synthase inhibitor N G -nitro-l-arginine methyl ester (l-NAME; Figure 1C). In endothelium-denuded aortic rings from control mice, acetylcholine induced a significant vasodilation if PVAT was left intact ( Figure I in the online-only Data Supplement). The PVAT-mediated vasodilation was preventable with l-NAME, indicating that PVAT-derived NO contributes to acetylcholine-induced vasodilation under normal conditions. Reduced NO Production in PVAT of Diet-Induced Obese MiceTo directly access NO production from PVAT, time-lapse fluorescence imaging was performed with aorta sections prepared from NCD or HFD-fed mice stained with the fluorescent NO probe 4,5-diaminofluorescein diacetate. As shown in Figure 1D, basal NO production could be detected in PVAT. The PVAT NO production was enhanced by ace...

Abstract-Adenosine is coupled to energy metabolism and regulates tissue blood flow by modulating vascular resistance.In this study, we investigated isolated, perfused afferent arterioles of mice, which were subjected to desensitization during repeated applications of angiotensin II. Exogenously applied adenosine restores angiotensin II-induced contractions by increasing calcium sensitivity of the arterioles, along with augmented phosphorylation of the regulatory unit of the myosin light chain. Adenosine restores angiotensin II-induced contractions via intracellular action, because inhibition of adenosine receptors do not prevent restoration, but inhibition of NBTI sensitive adenosine transporters does. Restoration was prevented by inhibition of Rho-kinase, protein kinase C, and the p38 mitogen-activated protein kinase, which modulate myosin light chain phosphorylation and thus calcium sensitivity in the smooth muscle. Furthermore, adenosine application increased the intracellular ATP concentration in LuciHEK cells. The results of the study suggest that restoration of the angiotensin II-induced contraction by adenosine is attributable to the increase of the calcium sensitivity by phosphorylation of the myosin light chain. This can be an important component of vascular control during ischemic and hypoxic conditions. Additionally, this mechanism may contribute to the mediation of the tubuloglomerular feedback by adenosine in the juxtaglomerular apparatus of the kidney.

There is considerable variation in IOP among the tested femtosecond lasers during a regular lamellar flap creation and during the worst-case procedure. The VisuMax femtosecond laser seems to cause the lowest IOP rise in both settings.