SALIDIURETIC ACTION BY GENISTEIN IN THE ISOLATED, PERFUSED RAT-KIDNEY

The urinary isoflavonoid genistein inhibits membrane Na-R-CI cotranspo rters at similar concentrations as furosemide, but the significance of this action is unknown, Genistein was therefore investigated in rats for its potential salidiuretic actions, In the isolated, perfused rat kidney, genistein induced a maximal salidiuretic action similar to tha t of furosemide but was 3 to 5 times less potent than furosemide In te rms of active doses (natriuresis EC50, 237+/-92 versus 56+/-20 mu mol/ L for genistein and furosemide, respectively). Genistein and furosemid e had no additive salidiuretic actions, Genistein had no significant e ffect on glomerular filtration rate but was able to significantly redu ce renal vascular resistance with respect to vehicle isolated perfused kidney, Indomethacin (10 mu mol/L), a blocker of prostaglandin biosyn thesis, reduced salidiuresis and renal vasorelaxation by genistein, Su bcutaneous genistein (ii mg/kg) induced a statistically significant in crease in diuresis and natriuresis with respect to vehicle during the first 6 hours of administration in rats. In conclusion, genistein comp ares well with furosemide in vitro for its salidiuretic profile and po tency in the isolated pet-fused rat kidney and is also natriuretic by the subcutaneous route in the rat. Further studies are required to inv estigate potential natriuretic and perhaps hypotensive actions of diet ary genistein.