Experiments were carried out on male white rats of Wistar strain, placed in metabolic cages in a room with artificial light and dark at 12-hour periods. Furosemide in a dose of 4 mg/kg was used intraperitoneally singly or after pretreatment with methoxamine in a dose of micrograms/kg or prazosin in a dose of 0.2 mg/kg. The renal excretory function was examined for a period of 2 hours. It was established that methoxamine usage increased diuresis without changing substantially sodium, potassium and total osmotic excretion. The application of furosemide after pretreatment with prazosin causes enhanced diuretic, sodium and chloruretic effect without potentiating potassium excretion. Separate examination of nephron functions by lithium clearance and its derivatives shows that alpha-adrenergic blockade reduces both proximal and distal resorption of water and sodium. The interaction of alpha-adrenergic agonist and alpha-adrenergic blocker affects chlorine excretion electively. After application of methoxamine the chloruresis, induced by furosemide, diminishes, but after prazosin pretreatment is increased.