Abstract
The kidney strictly controls the body Na+ content that is one of important factors determining the body fluid content and blood pressure by regulating the Na+ reabsorption in the distal nephron. The transepithelial Na+ reabsorption is mediated by epithelial Na+ channel (ENaC), which is controlled by aldosterone (ALDO), ADH and osmolality. A flavonoid, quercetin, which is contained in natural foods such as onions and soy beans is clinically reported to reduce high blood pressure. We previously reported that quercetin decreased the Na+ reabsorbtion in the distal nephron via suppression of _lpha-ENaC expression by activating the basolateral Na+/K+/2Cl- cotransporter. On the other hand, the ENaC expression is well known regulated by ALDO, however the interaction between ALDO and quercetin on the ENaC expression is not clear. To study the effect of quercetin on the ALDO-induced Na+ reabsorption through ENaC, we measured the benzamil-sensitive short-circuit current (Isc) as Na+ reabsorption in renal epithelial A6 cells. Although quercetin did not affect the basal Na+ reabsorption in ALDO-untreated A6 cells, quercetin reduced the ALDO-induced Na+ reabsorption dose-dependently by decreasing the benzamil-sensitive conductance. We suggest here that quercetin suppresses the ALDO action on ENaC. Supported by JSPS 15659053 (YM), 15590189 (NN), 15790120 (HM). [Jpn J Physiol 54 Suppl:S69 (2004)]
