THK ACTION OF I'KRTAIX (JLAM) KXTKACTS AND DRl'US 

 UPON THE UTKRUS OF THK HAT. By M. Itac.aki. (From 

 the Laboratory of Physiology, Edinburgh University.) (VV^ith four 

 rtofures in the text.) 



(Received for pnhlicatiou 3I.<t July 1916.) ^ 



The uteru.s of the rat has been used for the investigation of drugs by 

 Calliburces (1), Franz (2), Dale (3), Fiihner (4), Guggenheim (5). 

 Gunn (6), Herring (7), although most observers have employed the uterus 

 of other animals for this purpose. In my experiments on the corpus 

 luteum (8) and extracts uf ovary (9) I chiefly made use of the uterus of the 

 rat, and in connexion with those experiments had occasion to make a 

 certain number of observations upon the effect of other animal extracts 

 and drugs upon it ; the results of these are given here. The technique 

 employed was the same as in the other experiments. 



The uterus of the rat offers certain advantages over that of larger 

 animals. (1) It can generally be easily- obtained. (2) Being small, only 

 a comparatively small quantity of the solution to be tested is recjuired. 

 (3) The spontaneous rhythmic contractions which it shows in oxygenated 

 Locke solution at 37° C. are from the beginning of immersion fairly regular, 

 whereas, as Kehrer lias pointed out, those of the uterus of the dog and 

 rabbit are apt to be irregular (10). Any change, therefore, which is caused 

 in the uterine movements can be easily observed. 



Fig. 1 is a typical tracing exhibiting the movements of the rat's uterus 

 under the above circumstances. It will be seen that it shows (juite regular 

 rhythmic contractions. The ascending part of each curve indicates con- 

 traction ; the descending part, relaxation. The contraction starts fairly 

 quickly, slows down towards the apex of the curve, and, after the 

 maximal contraction is reached, comes down at first rapidl}- and then 

 more gradually. With the weight of lever employed by me the duration 

 of contraction was shorter than that of relaxation. The rhythm of the 

 contractions of the rat's uterus under these circumstances is, roughly, one 

 per minute. 



Incidentally, I find that if the uterus is excised and kept in Locke 

 .solution in an ice-chest at a temperature of between 3° and 7° C, even for 

 as long as three days, it still responds when immersed in oxygenated Locke 

 solution at 37' C. A somewhat similar observation was made by Hudston, 



