EFFECTS OF ALPHA- AND BETA-SYMPATHOMIMETIC AMINES AND BLOCKING AGENTS ON RENAL EXCRETION AND REABSORPTION OF FLUID AND ELECTROLYTES IN RATS

The renal excretion of fluid, sodium and potassium has been measured in unanaesthetized rats after oral loading with water. Subcutaneous injections of 0.3 μmol/kg epinephrine had a small antidiuretic action, whereas the same dose of norepinephrine increased urine flow. 0.05 μmol/kg isoprenaline delayed the excretion of water and depressed the excretion of Na and K. The effects of norepinephrine were unchanged after injecting phentolamine or propranolol. Epinephrine had a strong isoprenaline-like antidiuretic action after phentolamine but increased the urine flow like norepinephrine after an injection of propranolol. The actions of isoprenaline could be blocked by propranolol. In micropuncture experiments orciprenaline increased the intrinsic reabsorptive capacity of the proximal tubular epithelium when injected into the lumen of a proximal convolution. These effects are prevented by propranolol. Epinephrine and norepinephrine had no effects on tubular reabsorption in the proximal convolution. © 1969 Springer-Verlag.