110 ADVANCED LESSONS IN PKACTICAL PHYSIOLOGY 



ing drum. Occlude the tracheal cannula with the tip of your finger. 

 Observe that the respiratory movements gradually assume a labored 

 character and that the respiratory variations in blood-pressure are 

 thereby rendered more conspicuous. The blood-pressure rises grad- 

 ually. The frequency of the heart, which is increased at first, is soon 

 lessened. The heart then assumes a markedly diastolic character and 

 causes the blood-pressure to fall. Immediately remove your finger from 

 the tracheal cannula and wait until normal hemodynamic conditions 

 have again been established. What factors are involved in the initial 

 rise in blood-pressure? 



3. Effect of Amyl Nitrite. Place a glass bead filled with amyl 

 nitrite in a small glass bottle. Break it between the tongs of an artery 

 forceps. Place the palm of your hand over the mouth of the bottle. 

 Record the blood-pressure upon a slowly revolving drum. Allow the 

 animal to inhale the amyl nitrite by holding the end of the rubber tube 

 attached to the tracheal cannula in the bottle. Remove the tube from 

 the bottle as soon as the blood-pressure begins to fall. Naturally, the 



FIG. 71. EFFECT OF AMYL NITRITE ON BLOOD-PRESSURE (Doo). 



pressure will continue to drop even after this time until the amyl 

 nitrite, which has been absorbed from the inspiratory air, has been 

 rendered inert. Subsequent to this point, however, it will rise slowly 

 until normal conditions have again been established. Explain in detail 

 the action of this agent. 



What are the hemodynamic conditions established during attacks 

 of angina pectoris? What changes may be effected during these attacks 

 by inhalations of amyl nitrite? 



Replace the clip upon the artery after each experiment. If coagula- 

 tion has set in, flush out the tubing as well as the cannula with sodium 

 carbonate solution. 



4. Effect of Adrenalin. Add 1 c.c. of adrenalin (solution 1 : 1000) 

 to 10 c.c. of saline solution. Expose the right external jugular vein. 

 Place a clip upon it centrally and insert a cannula distally to the clip 

 (toward the heart). Fill the cannula with normal saline solution and 

 connect it by means of a short piece of rubber tubing with a pipet 

 containing the aforesaid solution of adrenalin. Fasten the pipet in a 



