Effects of Salt on Serum Osmolarity and Hemodynamics Parameters
Condition: Hypertension; Sodium Excess; Oxidative Stress; Inflammation
MeSH terms: Hypertension; Inflammation
Study type: Interventional

Summary: 
      Diets containing excessive salt (>12 g/day) have negative effects on kidney and
      cardiovascular system. Considering this known fact, the investigators aimed to study if the
      amount of the water taken with excessive salt had any part on these negative effects by
      testing the blood pressure, serum osmolality, endothelial functions, cardiac function,
      inflammatory parameters and sympathetic nervous system.

      Excessive dietary salt raises the serum osmolality, which triggers the protection mechanisms
      of the body. The first mechanism is the secretion of vasopressin from posterior pituitary and
      the second one is the polyol mediated aldose reductase enzyme activation in renal tubules. In
      the beginning, water and a little amount of salt is reabsorbed from the kidneys for keeping
      the serum osmolality in normal ranges by the elevation of vasopressin. Besides the high
      levels of vasopressin for long durations may have a role in both developments of hypertension
      and the progression/development of chronic kidney disease. Polyol mediated aldose reductase
      enzyme turns glucose into sorbitol, which is turned to fructose by sorbitol dehydrogenase
      activity. Fructose is degraded by fructokinase activity into toxic substances. With this
      pathway, the acute energy need is satisfied, yet uric acid, local oxidative stress, and
      inflammatory mediators rise while nitric oxide levels decreasing. These facts are independent
      risk factors for both kidney disease progression and hypertension. In addition, excessive
      salt intake may elevate the transforming growth factor beta-1 (TGF-B1) levels, which
      activates the sympathetic system, inflammation, and endothelial dysfunction.

      According to these data, the investigators speculate that if they increase the amount of
      water intake while eating the high salt diet they may decrease the toxic effect of salt with
      less increase in serum osmolarity. To test this hypothesis, by regulating the salt and water
      amount in healthy people's diets, the investigators aimed to evaluate the following these
      parameters; biochemical parameters that could affect the blood and urine osmolality, blood
      pressure, vascular endothelial functions with the non-invasive flow-mediated dilatation
      technique and arterial stiffness, systolic and diastolic functions of the heart by
      transthoracic echocardiography. In addition, it was planned to evaluate the hormonal effects
      of arginine vasopressin, a long peptide with 39 amino acids, which is longer and easier to
      measure than vasopressin levels in serum by measuring the pituitary hormone-derived copeptin.

      Although, decreasing the salt intake is the first step of the treatment in hypertension, and
      kidney diseases, the compliance rate to less sodium intake is very low (<20%). The
      investigators aim is to evaluate the effects of water, which is taken acutely with the
      excessive salt intake on cardiovascular system and kidney. The findings of the study will
      important for public health. If the investigators prove their hypothesis, they may recommend
      increasing high water intake before feeling thirst of which may contribute to decreasing the
      prevalence of hypertension and kidney disease.
    


Intervention name(s): High salt (NaCl) intake
Intervention type(s): Other
Intervention description(s): Participants are asked to consume two high sodium-containing soups while monitoring their serum osmolarity levels
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: Osmolar Concentration; Oxidative Stress; Salt; Inflammation; Endothelial Function; Hypertension