ERGAMINE AND ADRENALINE 



367 



centimeters to one milligram) and record the results. Do 

 you get a contraction of the uterus? How is the blood-pres- 

 sure affected! The respiration? If the animal is about to 

 die inject one cubic centimeter of adrenaline and see how 

 this counteracts the respiratory and vascular actions of the 

 ergamine. Does this affect the uterus! In what ways may 

 the adrenaline act to change the respiration of this animal? 

 Wait a while and let the animal recover (if necessary). 



VA+t.. .? 



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Fig. 308. Tracing showing the action of ergamine (histamine) and adrenaline on 

 the respiration (stethograph drum around chest) and blood-pressure in a dog. Ergamine 

 causes profound tetanic contraction of the bronchioles and shrinkage of the volume of 

 the lungs. This makes more difficult (and hence decreases) the normal respiratory 

 movements. This action may be accompanied by more or less depression of the respira- 

 tory center by the drug but the peripheral action is so powerful that it must be greatly 

 concerned in the decrease of the respiratory movements. Adrenaline (which dilates the 

 bronchioles) promptly relieves the respiratory embarrassment. Down stroke is .inspira- 

 tion. Does the animal have difficulty in inspiration or expiration? How does the 

 adrenaline affect this? How is the intrathoracic pressure affected? 



