390 AMYL-NITRITE 



vulsions and asphyxia ensue ; and the blood acquires a 

 chocolate hue. This has occasionally occurred in animals, 

 but is not easy to produce. The chief action of this, as of 

 the other nitrites, is to paralyse involuntary muscle (un- 

 striped) all over the body. From paresis of their muscular 

 wall the arterioles are rapidly and greatly relaxed and 

 dilated, and blood pressure is diminished. From the fall 

 of blood pressure there is less work for the heart to do, and 

 so a nitrite indirectly stimulates an overworked heart. 

 The unstriped muscle of the bronchioles is also similarly 

 affected and the tubes dilated. Secretion of sweat and 

 urine is increased, and the urine contains sugar. Human 

 patients receiving one to two minims within a few minutes 

 are flushed ; perspiration overspreads the head and neck, 

 extending sometimes over the body ; there is general 

 vascular dilatation ; arterial pressure is reduced ; the 

 temperature falls, the pulse becomes soft, quickened, and 

 dicrotic ; breathing, at first accelerated, becomes slower 

 and shallower. Similar symptoms are produced in dogs, 

 in which the temperature may be lowered 3 or 4 Fahr. 

 The antidotes are stimulants, alternate hot and cold douches, 

 artificial respiration, and inhalation of oxygen. 



MEDICINAL USES. It has been successfully used in 

 spasmodic breathing occasionally occurring as a sequel 

 of sore-throat and bronchitis. In such asthmatic cases 

 in horses and also in dogs it was used by Robertson. Ex- 

 periments on rabbits made artificially epileptic have shown 

 that it not only prevents the impending fit, but arrests 

 it when it has begun. It hence deserves more extended 

 trial in epilepsy in dogs and young cattle. Richardson 

 found that amyl-nitrite, promptly administered to rabbits 

 and frogs, which had received lethal doses of strychnine, 

 relieved the tetanic spasms and generally ensured recovery. 

 For tetanus in horses it has been frequently given, but 

 seldom with lasting benefit. In horses and dogs it is useful 

 as an inhalation in bringing about recovery from deep 

 chloroform anaesthesia. 



DOSES, etc. Horses and cattle take H\x. to TT\lx. ; dogs, 

 Tl\i. to TT\v. A minimum dose should first be tried. When 

 given hypodermically half doses generally suffice. Repeated 



