ACTION OF THE NITKITES 311 



Blood. — In poisoning by the nitrites, ' the oxidizing 

 power of the blood is lost. Both the venous and arterial 

 blood become of a chocolate hue from the conversion of the 

 normal oxy-hsemoglobin into meth-hasmoglobin. The latter 

 yields up oxygen very sparingly. 



Eespiration. — ^The respiratory .movements may be in- 

 creased both in force and frequency by medicinal doses of 

 nitrites, but paralysis of the respiratory centre and asphyxia 

 occiTrs in fatal poisoning. 



Eliminatipn. — The nitrite group rapidly escape in the 

 urine as nitrites and nitrates of the alkalies. The amyl, of 

 amyl nitrite, is completely oxidized in the body, while of 

 nitroglycerin part is eliminated unchanged in the urine. 



Summary. — The nitrites dilate arterioles, increase the rate 

 of the heart-beat, depress the spinal motor area, and lessen 

 reflex action. They relieve spasm and may increase the 

 secretion of urine. 



Poisoning. — Fatal poisoning is extremely rare as an 

 accidental occurrence. Recovery from a quantity 120 times 

 greater than the normal dose of nitroglycerin, has been 

 reported in' human practice. The physiological effects of 

 the nitrites are more noticeable in man, owing to his bare 

 skin. Immediately following the inhalation of amyl nitrite, 

 the face becomes extremely flushed, and throbbing of the 

 vessels of the head, with a feeling of tremendous pressure 

 and headache, ensue. These symptoms are due to vascular 

 dilatation. There is dizziness, the heart is rapid and violent, 

 and the pulse full, frequent and easily compressible. The 

 respiratory movements are increased. These symptoms occur 

 after a full medicinal dose. 



In poisoning there is pallor, vomiting in man, trembling, 

 Aveakness, cyanosis and failure of respiration and heart. 

 The treatment is included in the administration of ammo- 

 niacal and alcoholic stimulants, together with the subcuta- 

 neous injection of ergotin, strychnine and atropine, to restore 

 the vascular tone. 



The nitrites differ sufficiently to call for a word con- 

 cerning their individual characteristics. It is important to 

 emphasize the fact that their action, as a whole, is transient.- 

 Amy]- nitrite diminishes vascular tension, as shown by the 

 sphygmograph, within a minute of its inhalation, and this 



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