106 VASOCONSTRICTORS 



Dose. H. gr. %—Yi] 0.013—0.03. JJ. gr. i/ioo— Yoo ; 

 O.UOOG— -0.001. 



It is official as Spiritus Glycerylis Nitratis (Spirit of Glonoiu), 

 Spirit of Kitroglyceriu, a 1 per ceut. solution by weight. 



Dose. II. OSS — ij ; 2 — 8. 1). ITL j — iij ; 0.05 — 0.2 mil. 



Erythrol Tetranitrite is a slightly volatile solid, insoluble iu 

 water and very explosive. 



Dose. D. gr. i/e— j ; 0.01—0.05. 



Spiritus .ffitheris Nitrosi, Sweet Spirits of Nitre, is a 4 per 

 cent, by weight, alcoholic solution of Ethyl Nitrite. It is too mild 

 to be used as a general arterial dilator but is used in colds and slight 

 fevers as a diuretic. 



Potassii Nitras, potassium nitrate (Ivalium nitrate, nitre, salt- 

 peter) is a constituent of gun powder, but is non-explosive. It is 

 used in human practice for its nitrite action, by burning unsized 

 paper impregnated with it, to relax the spasmodically contracted 

 bronchial muscles in asthma. 



Action Circulatory System. 



Arteries. These are dilated by direct depression of the arterial 

 muscles, as is shown by the fact that the flow of fluid will increase 



Fig. 14. — Blood Pressure tracing. Horse. Effect of Nitroglycerin upon blood 

 pressure. (Tracing made by Dr. P. A. Fish.) 



greatly when a nitrite is added to the perfusing fluid, and since, if 

 the experiment is so carried out that the blood from the carotid will 

 reach the medullary centers, but is prevented from getting into the 

 general circulation, the injection of a nitrite into the carotid does not 

 cause a fall in blood pressure. It is, therefore, believed that the 

 centers are not involved. On the other hand, it is not known just 

 how much of the action is due to the effect upon the nerves "and 

 muscles but the dilatation takes place in the pulmonary arteries which 

 have no vasomotor nerves, so it is generally believed that the action 

 of the nitrites is due to direct depression of the arterial muscles and 

 they are, therefore, considered as true arterial dilators. 



