[Mechanism of action of diuretics studied by a fluorescent probe method]

The mercuric-xanthine diuretic novurit, ethacrynic acid and furosemide reduced the fluorescence of 1,8-anilinonaphthalene-8-sulfonate (1,8-ANS) in a suspension of phospholipid liposomes and human serum albumin solution. Ethacrynic acid and furosemide eliminated the fluorescence of 1,8-ANS in a suspension of non-energized mitochondria of rat kidney, while novurit provoked fluorescence intensification. The constants of novurit and ethacrynic acid binding with kidney mitochondria determined by the degree of changes in 1,8-ANS fluorescence variation appeared significantly higher than the constants of binding with phospholipids and serum albumin. However furosemide did not show a predominant binding with kidney mitochondria.