RESUMEN
BACKGROUND: The present study was aimed at investigating whether there is a mechanism exerted by endogenous nitric oxide(NO) in the regulation of aquaporin(AQP) water channels in the kidney. METHODS: Male Sprague-Dawley rats were treated with N(G)-nitro-L-arginine methyl ester(L-NAME, 40 mg/L drinking water) to inhibit the endogenous generation of nitric oxide. Four weeks later, total abundance and shuttling of AQP2 proteins were determined in different regions of the kidney. RESULTS: Chronic inhibition of NO synthesis increased the expression of AQP2 channels in cortex, outer medulla, and inner medulla of the kidney. The AQP2 shuttling was not significantly altered, as evidenced by an unaltered ratio of AQP2 expression in the membrane fraction versus that in the cytoplasmic fraction. CONCLUSION: It is suggested that endogenous NO activity plays a tonic inhibitory role in the expression of AQP2 channels in the kidney.