222 R. G. HOSKIKS 



epinephrin in the brain as a whole would not he expected, or possible. 

 That epintphrin does produce some effect in the vessels of the exposed 

 brain, however, has been demonstrated. Spina (1897) showed that intra- 

 venous injections of the drug result in marked dilatation of the cerebral 

 vessels (Biedl). This obviously might be explained as a passive result 

 of the general increase in arterial pressure. Biedl and Reiner showed 

 that direct application of epinephrin to the cerebral vessels induces con- 

 traction. This contraction was overcome, however, when epinepihrin 

 reached the general circulation and caused increase in tension. Wiggers(a) 

 (1905) perfused the cerebral vessels with Locke's solution to which epi- 

 nephrin was added. This resulted in contraction of the blood-vessels. 

 Thus it is evident that these vessels are capable to some extent of reacting 

 to epinephrin and that the reaction is primarily in the direction of contrac- 

 tion, at least with larger doses. So far as the writer is aware no deter- 

 minations have been made of the reaction under approximately normal 

 conditions. The quantitative relationships are especially in need of 

 further study. 



Effects of Epinephrin on the Heart. The work of Oliver and Schafer 

 and of the other earlier observers showed conclusively that epinephrin 

 has a marked stimulating effect upon the cardiac tissue. This effect may 

 be and often is more or less masked by concomitant stimulation of the 

 vagus mechanism, whereby the heart is depressed. These facts have long 

 since become commonplace observations in student laboratories of pharma- 

 cology and physiology. That the stimulating effect of epinephrin in the 

 heart as elsewhere depends upon the influence of the drug upon the sympa- 

 thetic nerve terminals is generally believed. Biedl has offered direct evi- 

 dence that such is the case. He studied the effects of epinephrin upon the 

 heart of the embryo chick and found that it failed to respond to epinephrin 

 until its sympathetic innervation was established. 



Burridge (1917) has studied the effects of epinephrin on the heart in 

 relation to the various inorganic salts present in the blood-stream. When 

 frogs' hearts were perfused with saline solutions he found that traces of 

 epinephrin render the balance between the inorganic constituents of such 

 solutions of secondary importance as regards their suitability for the 

 maintenance of cardiac activity. Unbalanced Ringer's solution, which 

 contained too much calcium, too little calcium, or a considerable amount 

 of potassium, interfered with the cardiac activity. Traces of epinephrin, 

 however, rendered such unbalanced solution capable of maintaining cardiac 

 activity and of preserving in great measure the resemblance between the 

 behavior of the heart perfused with these solutions and with blood. Bur- 

 ridge believes that traces of epinephrin are constantly supplied to the blood 

 and play an important role in facilitating cardiac functions. 



It has been claimed by Danielopolu and Danulescu (1916) that epi- 

 nephrin may exert a strikingly beneficial effect in heart block. To a patient 



