. The endocrine organs; an introduction to the study of internal secretion . s ~ ta * fcfl P- 3 O O O . o - ,0 0 a preliminary fall precedes the rise produced by the first dose. Probably,therefore, there is present in the extract a second autacoid which isantagonistic to the first and should be classed with the chalones or in-hibitory autacoids. The substance which causes the fall of blood-pressureis not choline, although the curve obtained resembles that caused by quick, and <pv\a£is, protection. Effects of Extracts of Posterior Lobe of Pituitary 87 choline, for it is not affected by atrop
. The endocrine organs; an introduction to the study of internal secretion . s ~ ta * fcfl P- 3 O O O . o - ,0 0 a preliminary fall precedes the rise produced by the first dose. Probably,therefore, there is present in the extract a second autacoid which isantagonistic to the first and should be classed with the chalones or in-hibitory autacoids. The substance which causes the fall of blood-pressureis not choline, although the curve obtained resembles that caused by quick, and <pv\a£is, protection. Effects of Extracts of Posterior Lobe of Pituitary 87 choline, for it is not affected by atropine. In birds only dilatation of vesselsis produced, and this is antagonised by atropine (Noel Paton and Watson).On the hearts action the repeat dose has the same effect as the firstdose, the beat is strengthened (Biedl). The effect on the uterus (seebelow) is also repeated if administration of the autacoid is repeated. Thepressor effect and the effect on the heart produced by the stimulating(hormonic) autacoid usually lasts a considerable time (a quarter to half an. FIG. 58.—Tracing to show the effect of the addition of extract of posterior lobeof pituitary body to Ringers solution in which a longitudinal strip ofintestinal muscle was suspended. (A. W. Young.) Notice both the increasein force of the individual contractions and the increase in tone of the muscle. hour or more), varying, however, with the dose; the depressor effect of thechalonic autacoid has a much shorter period of activity. The extract of pituitary acts upon other plain muscular tissue besidesthat of the blood-vessels. Thus it powerfully affects the bladder andintestine (fig. 58) (Blair Bell and Hick), the stomach (Houssay),1 the uterus(fig. 59) (Dale),2 even in minute doses; it also produces dilatation of the pupil 1 Houssay states that the secretion of gastric juice is at the same time increased ; this isperhaps the result of setting up contractions in the muscularis mucosae. 2 The uterus is also re
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