B ARIU M-EPINEP II R 1 X A XT AGO XISM 



43 



no longer obtainable on occlusion of the arteries. Resuscitation 

 can frequently be repeated with Ringer's solution a number of 

 times before a condition is reached when it is no longer effective. 



16 (1976) 



Barium-epinephrin antagonism on the excised surviving 



intestine. 



By GEORGE B. ROTH 



[From the Pharmacological Laboratory of the Medical School, 

 Western Reserve University, Cleveland Ohio] 



Experiments conducted recently on the excised surviving in- 

 testine of the frog, showed that the barium contraction could be 

 wholly or partially removed by epinephrin (Arch. Inter, de 

 Pharmacodyn. et de Therap. Paper in press). 



Inasmuch as the frog's intestine in Tyrode's solution, reacted 

 to pilocarpine in an unexpected, heretofore undescribed manner, 

 namely, to produce relaxation, it was thought that the barium- 

 epinephrin antagonism was peculiar to the frog. 



Further experiments, in which excised surviving intestinal seg- 

 ments, from the turtle and rabbit were used, showed that the 

 barium-epinephrin antagonism could be demonstrated in these 

 animals. For example, in the turtle, the contraction caused by 

 10 mg. of barium chloride was completely antagonized by 0.4 

 mg. of epinephrin. This is, of course, contrary to the current 

 conception that barium act, directly on the contractile substance 

 and epinephrin on the receptive mechanism. 



This antagonism does not seem to have been previously de- 

 scribed in the literature; however, Professor A. N. Richards in- 

 forms me that he also had observed it in the excised rabbit's 

 intestine. 



