The Lack of Effect of Oral Doses of Cinchona Alkaloids on the Circulation of Dogs with Renal Hypertension

The effect of repeated oral doses of quinine and quinidine on the circulation of dogs with renal hypertension was studied with measurements of arterial blood pressure and renal hemodynamics. Alkaloid concentrations up to the toxic range had little effect on the blood pressure or renal blood flow. It is pointed out that this lack of effect is in contrast to the vasodilator action of these agents in normal and neurogenic hypertensive dogs. These experiments are interpreted as constituting support for the thesis that the cinchona alkaloids have their vasodepressor effect by virtue of a blockade of sympathetic neuromuscular vasomotor junctions.