Comparison of Effects of Cyanide and Acetylcholine on Renal Hemodynamics and Sodium Excretion

The present study compared the effects of acetylcholine to cyanide under the same experimental conditions of renal clearance in anesthetized dogs. Since cyanide is one of the few drugs for which the mechanism of action is known (cytotoxic hypoxia), some insight may be gained into the renal effects of acetylcholine since both produce direct natriuresis and diuresis. Infusion of 0.2 μg/kg/min of acetylcholine and 12.0 μg/kg/min of sodium cyanide into the left renal artery resulted in similar effects, i.e., increased fractional excretion of sodium, potassium, calcium, and magnesium. These effects were immediate and ipsilateral. Both agents increased the renal plasma flow to the same extent. In addition, regression plots of the relation between changes in sodium excretion and changes in renal plasma flow were similar for both agents. The pattern of similar renal functional changes suggested that acetylcholine is not a mere renal vasodilator but that its action is also mediated through alterations on direct tubular transport of ions.