316 EXPERIMENTAL PHARMACOLOGY 



of the ventricle before the manometer can be connected up. 



The pulmonary manometer should have its own inde- 

 pendent base line (which can be a wire fastened to the 

 board of the manometer). It is most instructive to the stu- 

 dent to use mercury in this manometer but sometimes wa- 

 ter or salt solution is used instead. The comparison with 

 the carotid pressure is seen at once if mercury is used. 



Sodium citrate solution is used to prevent coagulation. 

 A T-tube placed in the tube going down from the pressure 

 bottle permits each manometer to have its own supply of 

 citrate solution. When the cannula and tubing are all ad- 

 justed for the pulmonary pressure (the manometer should 

 have been fully adjusted previously) then wash out the 

 tubes and manometer with citrate solution and fill the tubes 

 full but leave no positive pressure in the tubes. This is of 

 great importance. To accomplish best results a slight neg- 

 ative pressure in the tubes is advisable. To get this fill the 

 tubes and close both pinch cocks. Then open only the one 

 on the washout. The pressure falls to zero in the manom- 

 eter. Now between the thumb and finger squeeze the tube 

 from the artery to the manometer. A small amount of the 

 citrate solution runs out. Now close the washout and let 

 go the tube. A slight negative pressure shows in the ma- 

 nometer but the tubes are full of solution and no air is left 

 in them. 



Work rapidly now for the animal may die soon and a 

 clot is very liable to form in the pulmonary cannula. Ad- 

 just all writing points, remove the pulmonary bull-dog and 

 take a short normal tracing. Inject one-half cubic centi- 

 meter of adrenaline and get a record. What effect has 

 this on pulmonary pressure ? Does the pressure rise 

 higher in the right lung than it does in the left? Does 

 your experiment demonstrate this? Explain. What nerv- 

 ous structures are involved in this reaction? 



As soon as the normal is reached inject a dose of nico- 

 tine (three-fourths cubic centimeter). Do you get a satis- 



