Abstract

With the longer life expectancy and population aging, chronic diseases such as diabetes, hypertension, and cardiovascular disease, are main drivers of population health. With these demographic changes, medicine has switched its perspectives on how these conditions should be managed. In contrast to the classic approach that relied mostly on drug-based treatments, independent of their improved efficacy, now disease prevention, emphasizing healthy behaviours, has gained substantial attention. Therefore, keen interest in modifying unhealthy lifestyles has emerged as an extremely relevant strategy to improve life quality and reduce disease burden. A modifiable unhealthy behaviour is dietary sodium (salt) intake, for example. Extensive literature supports that our diets, mostly derived from processed foods, contain a large excess of sodium in detriment of potassium. Currently, daily sodium dietary intake averages 120 mmol and 70 mmol potassium, which have been directly associated with mild hypertension. In contrast, diets rich in fresh fruits and vegetables have a positive ratio of potassium over sodium, with a daily potassium intake of approximately 200 and 70-80 mmol of sodium, respectively. This dietary modification has achieved reductions in stroke and other cardiovascular disease. In addition, the introduction of nutraceuticals, based on trace minerals, unsaturated oils such as omega 3, natural products and/or vitamins derived from vegetables and fruits, have enriched and improved the quality of people’s diets by decreasing the severity of diabetes, hypertension, stroke, menopause and osteoporosis, among others. This project focuses in preventing vascular disease caused by diabetes. In patients with diabetes, increasing potassium dietary intake reduces the risk of stroke and other negative cardiovascular outcome. In addition, the supplementation of dietary antioxidants further reduces the severity and progression of vascular disease. Our current FONDECYT 114-1132 project has shown evidence supporting the protective effect of the K diet in the STZ-diabetic rats. Feeding rats for 2 weeks with a potassium supplement reduces endothelial dysfunction elicited by streptozotocin (STZ)-induced diabetes. Based on this finding, we now propose that diets rich in potassium plus antioxidant polyphenols enhance endothelium signalling impaired by diabetes likely in a synergic way. The ultimate goal of this proposal is to learn how potassium supplements, dietary antioxidant polyphenols, and the combination of these may help to restore endothelium dysfunction imposed by diabetes. These strategies might become novel alternatives to enhance endothelium functioning and therefore decrease the progression and severity of vascular disease. In this proposal, we will examine: 1) the release of extracellular ATP from endothelial cells as an index of endothelium functionality, 2) the production of nitric oxide (NO), an endothelial vasodilator, and 3) the role of ADMA, an endogenous eNOS inhibitor in the arterial mesenteric bed and isolated endothelial cells from this vascular territory in STZ-diabetic rats and non-diabetic rats fed with and without a rich potassium diet, polyphenols supplement, and both supplements. Specific aims of this proposal are to determine: 1. The vasodilation mechanism of potassium rich diets. We hypothesize that this diet increases endogenous ATP release and subsequent NO production. We will examine increased secretion of vasodilator purines released by mechanical stimulus, mimicking shear stress stimuli in both perfused vascular beds and isolated endothelial cells. We will evaluate whether this effect occurs in endothelial cell cultures as a simpler means to understand nucleotide metabolism and its release as an index of endothelium signalling and its influence on vascular wall reactivity in normal and diabetic-rats. 2. The mechanism how polyphenols increase NO production. We propose that natural or synthetic polyphenols are positive allosteric eNOS regulators. Preliminary results detected a polyphenol binding site in the oxygenase domain of crystallized human eNOS. To investigate whether this site is related to the purported antioxidant and vasodilator activity of natural or synthetic polyphenols in the rat mesenteric bed, we will investigate the relative potency of a series of natural and synthetic flavonoids as vasodilators and NO producers in this vascular territory. We will correlate the binding energy (-ΔG kcal/mol) of these compounds for the putative site with vasodilator potency as well as their effectiveness to produce NO in this vascular bed. Moreover, we will assess whether the antioxidant potential of these compounds correlate with NO production to understand whether polyphenols protect biopterin, the eNOS cofactor, from oxidation, enhancing by double novel mechanisms NO production. 3. The mechanisms of potassium plus polyphenols dietary supplementation ameliorating the detriment of diabetes-related endothelium functioning. We aim to discover treatment synergism. These investigations will explain the physiological/biochemical mechanisms of interventions that have the potential to increase the quality of life and reduce the burden of disease of Chilean citizens