Study group discussion: Why does ingestion of salt cause high blood pressure?

Why does salt increase blood pressure? I Googled it but there is no biochemical info.

Salt in the blood takes water out from cells into veins and here we got blood pressure.

Excessive NaCl ingestion or NaCl retention by the kidneys and the consequent tendency toward plasma volume expansion lead to hypertension. Nevertheless, the precise mechanisms linking salt to high blood pressure are unresolved. The discovery of endogenous ouabain, an adrenocortical hormone, provided an important clue. Ouabain, a selective Na+ pump inhibitor, has cardiotonic and vasotonic effects. Plasma endogenous ouabain levels are significantly elevated in approximately 40% of patients with essential hypertension and in animals with several forms of salt-dependent hypertension.
Source: http://www.ncbi.nlm.nih.gov/pubmed/16467498

I was reading about it and people on the internet believe that salt causing hypertension is a myth :/

It was also given on wikipedia, I donno how you missed it..

When too much salt is ingested, it is dissolved in the blood as two separate ions - Na+ and Cl-. The water potential in blood will decrease due to the increase solutes, and blood osmotic pressure will increase. While the kidney reacts to excrete excess sodium and chloride in the body, water retention causes blood pressure to increase inside blood vessel walls.