THE ACTION OF EPINEPHRIN UPON THE MUSCLE TISSUE 

 OF THE VEIN. 



BY J. T. M'CLINTOCK. 



The physiology of the venous circulation has, in comparison to that 

 of the arterial, received very little consideration. It has been looked 

 upon as a circulation carried on in a system of inert, elastic tubes, 

 carrying the blood back to the heart from the periphery and without 

 much, if any, physiological action on the part of the venous wall in 

 the process. We are in the habit of looking to the heart, the arterial 

 tension and the skeletal muscle action as being the forces driving the 

 blood thi'ough the venous system. 



The venous part of the circulation is of equal importance to the 

 arterial, for under the conditions as they exist the one cannot be with- 

 out the other and it is hardly to be expected that in so important a 

 process the tissue would be left with only the physical force of elas- 

 ticity upon which to depend for meeting the variable conditions to 

 which it must be sulijected. The attention now being given to the study 

 of the venous circulation and the physiological activities of the venous 

 wall has already given us a better understanding of phenomena con- 

 nected with the general circulation and has changed our explanations 

 of some of them. 



One of the most important of the problems connected with the gen- 

 eral circulation is that of surgical shock, a conditions which has been 

 commonly described as being primarily the result of an alteration in 

 the arterial portion of the circulation but the better understanding of 

 the venous circulation leads us to place the phenomena as of venous 

 origin and not arterial. It was in carrying out some experiments as 

 to the true nature of shock that the experiments here reported were 

 undertaken. 



In shock the condition which has been most commonly accepted is one 

 of extreme low arterial tension resulting from a more or less complete 

 fatigue of the vaso-constrictor centres. The natural constricting im- 

 pulses to the arteries then fail to pass through the centres, and without 

 these impulses the arteries dilate and a low blood pressure results. 



