ON THE DIURETIC ACTION OE DIGITALIS. 



In conjunction with HENEY POWEE, M.B., F.E.C.S. 



(Reprinted from tlie Froceedings of the Boyal Society, No. 153. 1874.) 



It lias been sliown, by Max Herrmann and Ludwig, that the 

 rapidity of the urinary secretion depends on the difference in 

 pressure between the blood in the renal glomeruli and the urine 

 in the urinary tubules. 



At present, it is generally assumed that the diuretic action of 

 Digitalis is not caused by any specific inliuence of the drug 

 upon the kidney, but is due exclusively to its power of increasing 

 the blood-pressure in the arterial system. 



The results of some experiments made by us nearly a year 

 ago show that this is not the fact. On injecting a considerable 

 dose of digitalin (1 — 2 centigrammes) into the veins of an 

 etherized dog, we have observed that the secretion of urine was 

 either greatly diminished or ceased altogether, while the blood- 

 pressure rose, occasionally to a considerable extent. After some 

 time the blood-pressure again fell; and in some of the experi- 

 ments the secretion of urine recommenced at the instant the 

 fall began. In other instances it did not recommence till the 

 blood-pressure had sunk below the normal. Occasionally the 

 secretion did not flow with its original rapidity, but in others it 

 was poured forth copiously, even although the blood-pressure 

 had sunk considerably below the normal. 



If Digitalis acted as a diuretic only by raising the blood- 

 pressure, the flow of urine should have been greatly increased 

 immediately after the injection, and should have diminished 

 with the fall of arterial tension. Instead of this the secretion 

 was least when the blood-pressure was highest, and most copious 

 when the tension had fallen below tlie normal. 



The explanation we would offer of these phenomena is, that 

 Digitalis probably stimulates the vaso-motor nerves generally. 



