Electrolyte Blood Press.  2005 Nov;3(2):82-90.

Pathogenesis of Postobstructive Diuresis: Role of Aquaporin Water Channels, Sodium Transporters and Natriuretic Peptide System in the Kidney in Rats

• Kim SW

Abstract

Although the obstruction is potentially reversible with treatment, marked and sometimes prolonged diuresis and natriuresis associated with an impaired ability to concentrate the urine may follow relief of the obstruction. Various factors contributing to the postobstructive diuresis and natriuresis have been suggested, including decreases of tubular sodium reabsorption, retention of urea and expansion of extracellular fluid volume. Tubular damage as a consequence of obstruction may occur one or more nephron segments and may result in decreased reabsorption of filtrate. The discovery of aquaporin (AQP) membrane water channels and sodium (co)transporters and channels provided insight, at the molecular level, into the fundamental physiology and pathophysiology of water and sodium balance. In addition, recent studies have shown that the kidney per se is also a site of production and release of atrial natriuretic peptide (ANP). The locally synthesized ANP may act in a paracrine manner to increase the urinary excretion of sodium and water. In this context, an altered regulation of ANP in the kidney may result in an altered urinary excretion. The combined interactions of multiple independent mechanisms are thought to be involved in the pathogenesis of postobstructive diuresis and natriuresis. We examined the changes of AQP water channels, sodium (co)transporters and natriuretic peptide system in obstructed kidneys. The expression of AQP water channels and sodium transporters was decreased in the obstructed kidneys, which may at least in part account for the urinary concentration defect associated with postobstructive diuresis and natriuresis. In addition, the postobstructive natriuresis was associated with an enhanced renal expression of ANP mRNA and an increased urinary excretion of ANP. The plasma dendroaspis natriuretic peptide (DNP) level was increased following an experimental ureteral obstruction. The urinary excretion of DNP was increased along with the postobstructive diuresis. An enhanced activity of DNP system may in part play a role in mediating the postobstructive diuresis

MeSH Terms

Animals
Aquaporins*
Atrial Natriuretic Factor
Diuresis*
Elapidae
Extracellular Fluid
Kidney*
Membranes
Natriuresis
Natriuretic Peptides
Negotiating
Nephrons
Physiology
Plasma
Rats*
RNA, Messenger
Sodium*
Urea
Ureteral Obstruction
Aquaporins
Atrial Natriuretic Factor
Natriuretic Peptides
RNA, Messenger
Sodium
Urea