VASCULAR NO AND SUPROXIDE PRODUCTION IS INFLUENCED BY HIGH DIETARY SALT INTAKE IN TFF3−/− MICE

Abstract

Objective: Arachidonic acid metabolism and products are shown to affect vascular reactivity mechanism. TFF3−/− mice have protective phenotype of favorable ratio of ω6/ω-3 fatty acids and modified metabolism of arachidonic acid. However, the role of TFF3 peptide in hypertension and vascular function is still underinvestigated. The aim of this study was to asses the effect of high salt diet on flow-induced endothelial NO and superoxide production in carotid arteries of wild type mice of mixed background C57Bl6/Sv/129 (WT) and TFF3−/− knock out mice with the same background. Design and method: Eleven weeks old male TFF3−/− or WT mice were divided in 2 groups (N = 4 per group): low salt (LS) and high salt (HS; 4% NaCl for 7 days). Following dietary protocol, mice were anaesthetized with ketamine (75 mg/kg) and midazolam (2.5 mg/kg). Carotid arteries were isolated and cannulated on pressure myograph with or without flow (at delta 80 mmHg), in the absence/presence of the NOS inhibitor L-NAME. NO production was determined by DAF-2DA to DAF-2T conversion fluorescence assay. To assess the production of superoxide radicals, the carotid arteries were loaded with dihydroethidine (DHE, 20 μM). All experimental procedures conformed to the European Guidelines for the Care and Use of Laboratory Animals (directive 86/609) and were approved by institutional Ethical Committee. p < 0.05 was significant. Results: Basal NO production in no-flow condition was similar among groups. L-NAME blocked the production of NO in all groups. Flow-induced NO production was decreased in HS-WT group compared to no-flow conditions in HS-WT group, and compared to LS-WT group and LS-TFF3−/− group (p < 0.05). There were no changes in endothelial NO production in TFF3−/− mice. Superoxide production was increased in LS-TFF3−/− no-flow group compared to LS-WT in no-flow condition Flow-induced superoxide production was increased in both HS-WT and HS-TFF3−/− groups compared to corresponding LS groups. Conclusions: HS intake decreases flow-induced vascular NO production in WT mice probably due to increased oxidative stress. However, HS intake does not affect NO production in TFF3−/− mice eventhough superoxide levels are increased in basal levels and in flow conditions, suggesting protective role of this phenotype on NO bioavailability.