314 DRUGS ACTING UPON THE GENITAL ORGANS 



upon a wliole group of nerve endings which have similar functions. 

 This results in constriction of the blood vessels, with a rise in blood 

 pressiire, and in contraction of those plain muscles which contract 

 in response to stimulation of the sympathetic. Ergotoxine resembles 

 the action of adrenaline in its effect upon the motor nerve endings 

 or their myoneural junctions of the sympathetic, but differs from 

 it in not stimulating those structures concerned in inhibition. 



Local Action. Ergot is irritant to mucous membranes and raw 

 surfaces. It does not constrict the vessels of the mucous membrane, 

 but when injected subcutaneously there may be a constriction of the 

 arteries at the point of injection. Local gangrene sometimes follows 

 its use. 



Digestive Tract. Preparations of ergot are irritant locally 

 and may cause nausea and vomiting, or, in poisonous doses, a violent 

 gastroenteritis. The alkaloids are not irritant. Therapeutic doses 

 of ergot decrease intestinal peristalsis by stimulating the ends of the 

 splanchnic (inhibitory) nerves, while very large doses cause in- 

 creased peristalsis by paralyzing these same nerve endings. This 

 action is not seen in the therapeutic use of the drug. 



Circulatory System. Ergotoxine or tyramin injected in- 

 travenously will cause a marked rise in blood pressure very similar 

 to that of adrenaline, but the rise is slower and its duration three or 

 four times as long; furthermore it may be obtained from oral or 

 subcutaneous administration. The constriction of the arterioles at 

 the site of injection is not so great as that from adrenaline but is more 

 persistent and has resulted in gangrene in some instances. The ac- 

 tion is peripheral and appears to be exerted upon the myoneural 

 junctions of the vasoconstrictor nerves. 



The isolated heart may be increased in rate and strength but in 

 intact animals may be slowed on account of increased blood pres- 

 sure. 



According to several writers the effect of tyramin in human 

 blood pressure is not marked when given per os and fairly large 

 doses were required to increase blood pressure when given hypo- 

 dermically. When obtained it resembles a retarded adrenaline ac- 

 tion. 



Although the active principles of ergot produce constant results, 

 the effect of the preparations of the crude drug are not certain. 

 Tt may produce either a striking rise or fall in pressure. The fall 

 is thought to be due to the presence of saponin bodies. It is not 

 practical, at least, to administer ergot in therapeutics for increased 

 pressure but its alkaloids may be used in emergency. 



Gangrene follows chronic poisoning and is probably due to the 

 prolonged powerful constriction of the arterioles which almost com- 

 pletely arrests the circulation. 



Chronic poisoning (ergotism) is easily produced in pigs and 



