Expression of organic anion transporters in rats with bilateral ureteral obstruction.

VILLAR, SILVINA RAQUEL; BRANDONI, ANABEL; ANZAI, NAOHIKO; ENDOU, HITOSHI; TORRES, ADRIANA MÓNICA

Buenos Aires

Congreso; XXII Congreso Latinoamericano y I IberoAmericano de Ciencias Fisiológicas; 2006

Sociedad Argentina de Fisiología

The obstruction of the urinary tract (BUO) impairs kidney functionality, and is characterized by profound changes in both renal hemodynamics and tubular functions. The tubular secretion of organic anions is an important function of the kidney, disposing of potentially toxic organic anions from the body. We have observed modifications in the renal clearance of organic anions in rats with BUO after 24 hours of ureteral realeasing (Kidney Int. Vol 68–2005-pp 2704-2713). The objective of this work was to study the renal excretion of p-aminohippurate (PAH) and the cortical renal expression of the organic anion transporters (OAT1 and OAT3) in BUO rats. Male Wistar rats underwent bilateral obstruction of the proximal ureters (BUO, n=6), which lasted 24 hours; a Sham-operated group (Sh, n=5) was also tested. 48 hours after ureteral releasing, the following studies were performed: PAH renal excretion employing conventional clearance techniques and OAT1 and OAT3 expression using immunoblotting and immunocytochemical techniques. BUO rats showed a renal clearance of PAH lower than Sham (ClPAH mL/min/100g b.w.: Sh=4.12±0.90; BUO=0.83±0.15*). Immunoblotting revealed significant decreases in the abundance of OAT1 in homogenates, intracellular membrane fractions, and basolateral plasma membranes (BLM) (OAT1BLM %: Sh=100±9; BUO=50±12*) from renal cortex in the obstructed kidney. Similar decreases were observed for OAT3, in homogenates and basolateral membranes (OAT3BLM %: Sh=100±6; BUO=47±3*), while values for intracellular vesicles did not change. (* p<0.05). Immunocytochemical assays confirmed these results. In conclusion, downregulation of OAT1 and OAT3 in rats with BUO may contribute to the impairment in the elimination of organic anions.