Abstract
Summary
The effect of various doses of ouabain was studied on the isolated perfused kidney. A pronounced and consistent diuresis and natriuresis did not occur until a dose of 0.085 mg of ouabain was used. Within 2-20 min after the administration of ouabain, renal vascular resistance increased causing an increase in perfusion pressure and a reduction in renal blood flow, urine excretion, sodium excretion, and creatinine clearance. Plasma potassium always rose after the administration of ouabain. At 20-60 min after the addition of ouabain renal vascular resistance fell, causing the perfusion pressure to return to normal. There was an increase in renal blood flow, urine excretion (+220%) p<0.01 sodium excretion (+215%) p< 0.02 and the creatinine clearance returned to normal. Plasma potassium remained elevated. When potassium chloride (KCl) was added to the perfusion after 3-4 control periods, the plasma K level was raised from an average of 4.9 meq/liter to 8.6 meq/liter and leveled off at 8.1 to 7.8 meq/liter after the addition of ouabain. A diuresis and natriuresis was also produced by the addition of KCl, but when 0.085 mg of ouabain was added 20-40 min after the addition of KCl, even greater diuresis (+147%) p<0.001 and natriuresis (+138%) p<0.01 were produced. There was little evidence for a K-induced inhibition of the ouabain diuresis and natriuresis.
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