IntroductionDrugs with marked haemodynamic action could alter the filtration rate and urine flow by affecting arterial pressur? and efferent renal arteriolar resistance. Moreover, drugs used in treatment of hypertension reduce renal blood flow and filtration rate: these results however represent undesirable sideeffects (GOODMAN and GILMAN, 1970).Previous authors have reported that spironolactone, mercurials, furosemide, ethacrynic acid and thiazides have an anti-hypertensive property beside their diuretic effect, but their mode of action in reducing arterial pressure remains unexplained. Some investigators attributed the resultant fall in arterial blood pressure to a reduction in the extracellular fluid and plasma