What causes salt retension in kidneys in a person on long term high salt intake?

Answer:
Salt retention in the kidneys are caused by 2 related factors. If you have low plasma salt concentration or low blood volume, the kidneys will retain salt and water to increase these intravascularly. Secondly, these low conc. of plasma sodium or low blood volume will cause several hormones tp come into play and these are the mechanisms of salt and water retention. (1) Aldosterone secretion by the adrenal glands, (2) secretion of renin by the kidneys, affecting angiotensin levels and causing the retention of sodium and water, also this will affect ADH (antidiuretic hormone) and ANF (atrial naturetic factor). Now these occur when there are low levels of sodium, low blood volume, as the result of certain medications and drugs or a combination. High salt intake usually blunts these responses because high NaCl causes water retention, increases blood volume and blood pressure.

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