Influence of Calcium and Barium on the Kidney. 189 



2. Calcium chloride diminishes not only the normal flow of 

 urine, but also that which is caused by the administration of saline 

 diuretics. For example, the rate of secretion which has been 

 largely increased by the intravenous injection of normal salt so- 

 lution may be temporarily lessened to a marked extent by the in- 

 troduction of CaClo into the blood. 



3. In all cases "/g solutions were used, and ""/g NaCl solution 

 was introduced into the blood at a constant rate throughout the 

 experiments. After a short time the rate of secretion became 

 constant. It was then found in rabbits, that the addition of a 

 small quantity of BaCL (^ cc ""/g solution) to the blood causes 

 a marked increase in the flow of urine, so that the amount of 

 fluid secreted may considerably exceed that which is introduced 

 mto the blood during the same period of time. 



4. This action of barium is counteracted by the injection of 

 CaCls. 



5. If a larger quantity of BaCL ( i cc ""/g solution) be added 

 to the blood, the flow of urine ceases and often complete anuria 

 ensues. In some cases the injection of CaCL abolishes this in- 

 hibitory action so that the urine flows again. Usually however 

 the action of barium persists. 



6. The fact that barium when given in smaller and in larger 

 doses may thus apparently have opposite effects on the flow of 

 urine may be explained by analogy with Its action on the intes- 

 tine. Barium chloride causes not only an increase in the secretion of 

 fluid into the intestine, but also active peristaltic movements, and 

 violent local constrictions of the Intestine. Similarly very small 

 doses of BaClg increase the secretory activity of the kidney. It 

 seems^ probable however that the cessation of the flow of urine 

 which follows the injection of larger quantities of the salt is due 

 not to an inhibition of secretion, but to the action of the barium 

 on the muscular coats of the urinary passages, especially those 

 of the calyces and pelvis of the kidney and those of the ureter. 

 This action would bring about a constriction of the tubes and a 

 closure of the lumen. The fact that calcium counteracts both 

 effects of the barium supports this explanation. 



