﻿PHAKMACOLOGIGAL ACTION 01*' UKAiMliM 



5 



might develop which would be entirely absent in an animal which 

 was killed by uranium in a relatively short period of time. In the 

 present instance I have not attempted to do more than to study 

 the immediate action of the drug. It may be said, however, that 

 in animals which die within an hour or so after the first injection 

 of uranium numerous small ecchymotic patches may be seen in the 

 intestinal mucosa. It is probable that in some cases such an action 

 as this might lead to the formation of lymph containing slight 

 traces of blood. If the capillary epithelium is weakened sufficiently 

 to allow the escape of a considerable amount of fluid from the 

 blood then this fluid is not, at least within the first two or three 

 hours, passed out of the thoracic duct. The significance which 

 this may have in relation to the production of edema when water 

 is administered to an animal after two or three days' treatment 

 with uranium I do not care to discuss. 



Action on the Circulation. A¥oroschilsky^ observed a rise in 

 blood-pressure which he attributed to stimulation of the vaso-con- 

 strictor center. I have corroborated his results and find that with 

 moderate injections (6 to 10 cc. of tAvo per cent solution) the 

 rise is at first only of a transient character. With repeated admin- 

 istrations, however, there is graduallj^ developed a tendency for 

 the pressure to maintain an elevation slightly above the normal 

 (Fig. 1). This seems to be at least partly due to a slight, con- 

 tinuous, but gradually increasing stim.ulation of the vaso-constrictor 

 center in the medulla. This stimulation is probably due in part to 

 a sort of compensatory (asphyxial) action by which the circula- 

 tion tries to counterbalance the gradually progressing depression 

 of the respiratory center. The increased volume of blood caused 

 by the rapid introduction of eight or ten cubic centimeters of 

 fluid into the circulation usually produces a slight rise of blood- 

 pressure lasting about as long as the injection continues. I have 

 observed that this elevation is often followed by a slight fall which 

 is also transient and may amount to twenty or twenty-five milli- 

 meters (Hg manometers) (Fig. 1). I believe this fall is mainly 

 due to a direct depressant action on the heart, for it also occurs 

 after section of the vagi, and sometimes I have noted after large 

 injections that the heart may weaken and miss one or two beats 

 and then gradually regain its normal strength. This may also 

 occur after section of the vagi. Seven or eight cubic centimeters 

 of a two per cent solution (UO^ changed to the double salt) gen- 

 erally produce a rise of about fifty millimeters of mercury in a 



8 Woroschllsky, loc. cit, p. 28. 



