[Effects of diuretics after pretreatment with reserpine and 6-OH-dopamine (author's transl)]

Experiments were performed on groups of 10 rats each with respect to the influence of systemic denervation by 6-OH-dopamine or reserpine on the diuretic effect of furosemide (3 mg/kg). In order to get a measure for the effectiveness of denervation, the tissue content of norepinephrine in kidneys, submaxillary glands, and hearts was determined by fluorimetric analysis. Neurotransmitter content: Chemical sympathectomy with 6-OH-dopamine resulted in a decrease of tissue norepinephrine down to 25% of the initial value in the kidneys, and down to 29 and 17% in submaxillary glands and hearts, respectively. After reserpine pretreatment the kidney norepinephrine was found decreased down to 28% of the initial concentration. Plasma electrolytes: Pretreatment with 6-OH-dopamine increased the plasma magnesium concentration considerably. Further administration of 3 mg/kg of furosemide had no additional effect. Plasma sodium, however, was significantly decreased, whereas potassium and calcium concentrations remained unchanged. After reserpine administration plasma calcium was found decreased. The effect was additionally enhanced by furosemide. Plasma sodium was found decreased, too, after furosemide, whereas potassium and magnesium remained unchanged after both reserpine and furosemide treatment. Fluid and electrolyte excretion: The diuretic effect of furosemide was not significantly influenced by both 6-OH-dopamine and reserpine pretreatment. In the reserpine pretreatment group, however, post furosemide sodium excretion was significantly increased as compared to the controls. In the 6-OH-dopamine pretreated group furosemide did not result in an enhanced natriuresis. In spite of a comparable depletion of intrarenal neurotransmitter after 6-OH-dopamine and reserpine, the kaliuretic effect of furosemide was obviously different in both groups. Reserpine pretreatment resulted in a decrease of the kaliuretic fuorsemide effect, whereas after 6-OH-dopamine this decrease could not be observed. The post furosemide calcium excretion was significantly increased after reserpine and unchanged after 6-OH-dopamine. Basic magnesium excretion was increased by the factor 2 in both groups, as compared to the controls. Administration of furosemide completely abolished this difference.