Water-Electrolyte Balance in Blood Pressure Homeostasis

Water-Electrolyte Balance in Blood Pressure Homeostasis Much of what human life is about is water (60% of body mass) and a handful of solutes. Of the latter, main cations include sodium, potassium, calcium, and magnesium, and the anions include chloride, bicarbonate, phosphate and organic anions, and proteins. The concentrations of sodium (135–145 mmol/L) and chloride (95–106 mmol/L) predominate in serum and constitute the bulk of serum’s osmolarity. In the course of evolution, complex regulatory mechanisms developed to keep the osmolarity (≈280 mosm/L) and thus amount of water at desired level. With it came the role of main solutes and their regulatory mechanisms (ie, renin–angiotensin–aldosterone system [RAAS]) in the regulation of blood pressure. Numerous studies demonstrated the role of sodium-based mechanisms in water homeostasis and blood pressure regulation. Recently, several well-designed studies showed that the level of ingested sodium correlated with the level of blood pressure or cardiovascular risk, and that the relationship is likely to assume a J-curve shape in population of patients with cardiovascular involvement or diabetes mellitus.