CARDIOVASCULAR CHANGES DURING CEREBRAL ANEMIA 7 



conditions, the various lesions did not materially change or delay the 

 picture of the recovery outlined. 



THE EXPERIMENTAL RESULTS. 1 . The role of the splanchnic constric- 

 tor fibers in the rise of pressure during cerebral anemia: Following the 

 work of Claude Bernard in 1848 who showed that the section of the 

 cervical cord caused a considerable fall of blood pressure, Bezold, Ludwig 

 and Cyons (46), (47), (48), (49), (50) measured- the magnitude of these 

 changes and showed their dependence on the integrity of the splanchnic 

 system. There was thus demonstrated the relation of the blood pressure 

 changes to the level which is maintained after the continuity of the cord 

 with the brain has been interrupted. 



Mall (51) showed that frequently 27 per cent of the blood in dogs was 

 transferred by the splanchnic system, thus explaining the great increase 

 of volume in the extremities during rises of systemic pressure (52). 

 Edwards (53) calculated that 85 cc. of blood in dogs were trans- 

 located under splanchnic stimulation. In spite of its probable involve- 

 ment in the powerful vasomotor response of the anemic rise, very little 

 direct evidence for its participation has been obtained. Hill's (46) 

 reference to the splanchnic nerves in cerebral anemia is, so far as can 

 be ascertained, largely by way of implication. For asphyxia itself 

 both V. Anrep (54) and Cathcart and Clark (55) have argued for con- 

 siderable splanchnic participation from the dependence on the central 

 nervous system of the adrenalin release obtained. Finally, some in- 

 direct evidence for splanchnic nerve involvement has been obtained by 

 section of the spinal cord in cerebral occlusion. Nawalichin (56) 

 found that the vasomotor changes following obstruction of the cere- 

 bral circulation were practically obliterated when the cord had been 

 sectioned in the cervical region. The same observation was made by 

 Stewart (28). 



In order to obtain any exact, or possibly even quantitative, evalua- 

 tion of the actual involvement of the splanchnic system, other factors 

 concerned in the maintenance and change of blood pressure must be 

 isolated. Three factors in the nervous regulation must above all be 

 properly controlled. These are (a), the indirect effect of the activity 

 of the skeletal muscles; (&), the influence of the cardiac innervation; and 

 (c), the non-splanchnic constrictor (or possibly dilator) fibers in the 

 vasomotor system. 



a. The influence of the skeletal muscles in the anemic rise. The 

 older authors, Mayer and Gouty, used curarized animals, rabbits and 

 dogs, for their experiments on cerebral occlusions, and reported anemic 



