Key Roles of Renal Aquaporins in Water Balance and Water-Balance Disorders

Key Roles of Renal Aquaporins in Water Balance and Water-Balance Disorders.

The discovery of aquaporins by Agre and co-workers provided an answer to the long-standing biophysical question of how water can pass cell membranes. The identification and characterization of several aquaporins expressed in the kidney has allowed detailed insight, at the molecular level, into the fundamental physiology and pathophysiology of renal water metabolism.

Aquaporins and plant water balance.

The impact of aquaporin function on plant water balance is discussed. The significance of these proteins for root water uptake, water conductance in the xylem, including embolism refilling and the role of plant aquaporins in leaf physiology, is described. Emphasis is placed on certain aspects of water stress reactions and the correlation of aquaporins to abscisic acid as well as on the relation...

Hyponatremia and hypernatremia: disorders of water balance.

Total body water and tonicity is tightly regulated by renal action of antidiuretic hormone (ADH), reninangiotensin-aldosterone system, norepinephrine and by the thirst mechanism. Abnormalities in water balance are manifested as sodium disturbances--hyponatremia and hypernatremia. Hyponatremia ([Na+ < 136 meq/ l]) is a common abnormality in hospitalized patients and is associated with increased ...

Water balance and hyponatraemia.

The role of aquaporins in cellular and whole plant water balance.

Aquaporins are water channel proteins belonging to the major intrinsic protein (MIP) superfamily of membrane proteins. More than 150 MIPs have been identified in organisms ranging from bacteria to animals and plants. In plants, aquaporins are present in the plasma membrane and in the vacuolar membrane where they are abundant constituents. Functional studies of aquaporins have hitherto mainly be...