The role of potassium-canrenoate on 3H-noradrenaline uptake and metabolism of the rat heart.

The influence of potassium-canrenoate (structurally related to spironolactones) on noradrenaline (NA) uptake and metabolism of the heart was studied in normal and hypopotassaemic rats. In normal rats spironolactone administration resulted in a marked increase of 3H-NA uptake in both the atrial and the ventricular tissues, but the NA content was unchanged. An increased myocardial NA uptake in the presence of an unchanged content suggested an increased rate of NA turnover under the influence of spironolactone. In saluretic pretreated animals, spironolactone normalized both the previously decreased NA uptake and the low intracellular potassium level of the heart tissue. The augmentation of catecholamine metabolism due to spironolactone may be involved in enhanced activity of adenyl cyclase and forms the basis of the compounds positive inotropic effect.