CHAPTER XXVI. 



The Direct Demonstration of Vasoconstrictor Fibres by 

 the Plethysmographic Method. 



Demonstration 2. The abdomen is opened in an etherised, 

 tracheotomised dog and the intestines retracted to the left side 

 under towels wrung out in warm saline solution. The great splanch- 

 nic nerve is isolated and a ligature placed around it on the right 

 side (see p. 83). The right kidney is freed from its bed and the folds 

 of peritoneum running to its upper end are cut after applying mass 

 ligatures. The pedicle is carefully freed by blunt dissection and 

 the plexus of nerves isolated from it and a ligature placed around 

 them. An oncometer, with cotton wool well mixed with vaseline 

 laid in the groove for the pedicle, is then placed under the viscus 

 and more cotton and vaseline placed in the groove until this is 

 filled (without any compression of the vein or ureter) after which the 

 glass lid is applied and clamped down. (There must be no strain or 

 kinking of the vessels during the manipulation). The side tube of 

 the apparatus is finally connected by moderately thick walled 

 tubing with a bellows recorder, the writing style of which is accur- 

 ately adjusted in the same perpendicular with the writing style of 

 a mercury manometer connected with the carotid artery. A re- 

 spiratory tracing should also be taken. On a moderately fast drum 

 tracings are taken to show the relationship of the oscillations of 

 the oncograph to the arterial and respiratory tracings. (What is 

 the relationship?) 



The effect produced on the kidney volume and the arterial 

 blood pressure is then observed: (1) during (electrical) stimulation 

 of the vagus in the neck; (2) during stimulation of the great splanch- 

 nic nerve on the right side (Fig. 61), and (3) during stimulation of 

 the renal nerves. How do you interpret the results? Why is the 

 arterial blood pressure essential in the interpretation? 



A small amount of physiological saline containing 1-10,000 

 adrenalin chloride is now injected into the femoral vein. What 

 conclusions do you draw from the result? 



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