AimTo test the early effect of fructose-induced changes in fatty acid composition and oxidative stress markers in perivascular adipose tissue (PVAT) upon vascular contractility.MethodsAdult male Wistar rats were fed a commercial diet without (CD) or with 10% fructose (FRD) in the drinking water for 3 weeks. We measured plasma metabolic parameters, lipid composition and oxidative stress markers in aortic PVAT. Vascular contractility was measured in aortic rings sequentially, stimulated with serotonin (5-HT) and high K+-induced depolarization using intact and thereafter PVAT-deprived rings.ResultsComparable body weights were recorded in both groups. FRD rats had increased plasma triglyceride and fructosamine levels. Their PVAT had an increased saturated to mono- or poly-unsaturated fatty acid ratio, a significant decrease in total superoxide dismutase and glutathione peroxidase activities and in the total content of glutathione. Conversely, lipid peroxidation (TBARS), nitric oxide content, and gluthathione reductase activity were significantly higher, indicating an increase in oxidative stress. In aortic rings, removal of PVAT increased serotonin-induced contractions, but the effect was significantly lower in rings from FRD rats. This effect was no longer observed when the two contractions were performed in PVAT-deprived rings. PVAT did not affect the contractions triggered by high K+-induced depolarization either in CD or FRD rats.ConclusionsFRD induces multiple metabolic and endocrine systemic alterations which also alter PVAT and the vascular relaxant properties of this tissue. The changes in PVAT would affect its paracrine modulation of vascular function.

Through their control of cell membrane potential, potassium (K þ ) channels are among the best known regulators of vascular tone. This article discusses the expression and function of K þ channels in human umbilical artery smooth muscle cells (HUASMCs). We review the bibliographic reports and also present single-channel data recorded in freshly isolated cells. Electrophysiological properties of big conductance, voltage-and Ca 2þ -sensitive K þ channel and voltage-dependent K þ channels are clearly established in this vessel, where they are involved in contractile state regulation. Their role in the maintenance of membrane potential is an important control mechanism in the determination of the vessel diameter. Additionally, small conductance Ca 2þ -sensitive K þ channels, 2-pore domains K þ channels and inward rectifier K þ channels also appear to be present in HUASMCs, while intermediate conductance Ca 2þ -sensitive K þ channels and ATP-sensitive K þ channels could not be identified. In both cases, additional investigation is necessary to reach conclusive evidence of their expression and/or functional role in HUASMCs. Finally, we discuss the role of K þ channels in pregnancy-related pathologies like gestational diabetes and preeclampsia.

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