Salt, water and nephron: Mechanisms of action and link to hypertension and chronic kidney disease

ABSTRACT

Our knowledge on sodium and water homeostasis and regulation continues to evolve. A considerable amount of new information in this area has emerged in recent years. This review summarizes existing and new literature and discusses complex multi‐organ effects of high‐salt and low‐water intake and role of arginine vasopressin in this process, as well as the potential clinical significance of non‐osmotic sodium storage pool and rhythmicity of urine sodium excretion. It has become clear that sodium and water dysregulation can exert profound effects on kidney and vascular health, far greater than previously recognized. Maladaptation to a combined high‐salt and low‐water intake can be linked to the growing epidemic of hypertension and chronic kidney disease.

Summary at a Glance

• Na ⁺ and water regulations are tightly connected, involving neurohumeral multi‐organ regulations of AVP, glucocorticoids, RAAS activation, muscle catabolism, urea generation and salt‐retention.

• High‐salt and low‐water intake, common in the general population, is potentially pathogenic and linked to the genesis of hypertension and CKD.

• The tissue (mainly skin and muscle) storage pool of Na ⁺ likely participates in Na ⁺ and water homeostasis; heavier tissue Na ⁺ storage may be pathological and has been associated with resistant hypertension and left ventricular hypertrophy.

• When appropriate, a modest increase (∼0.5 ‐1.5 L/day) in water intake and reduction in dietary salt to a recommended range can blunt AVP increase and will likely be beneficial.