Effects of morphine upon the isolated small intestine of rats, rabbits and guinea pigs.

Recently HUKUHARA, KOTANI and SATO7) found that morphine always exerted an excitatory action on the motility of dog jejunal Thiry-loop, literature concerned being reviewed there. They drew a conclusion that morphine acted as an excitant to the intestinal muscle itself, since it could raise the intestinal motility after atropine as well as hexamethonium had been administered and on the other hand it could augment the motility of the aganglionic loop. On the isolated guinea-pig small intestine, however, TRENDELENBURG15) concluded that the inhibition was the usual effect of morphine upon the socalled peristalsis'. This conclusion was supported by subsequent investigators.1, 9,10, 11,12) Our doubts were then cast upon the problem whether the discrepancy existing between our results and the investigators mentioned above could, in fact, be attributable to the species difference or not. In order to solve this problem the effects of morphine upon the motility of the isolated small intestine of rats, rabbits and guinea pigs were studied. In the present experiments the action of drugs was judged by observing the rhythmic contraction waves, which were recorded by means of MAGNUS' as well as TRENDELENBURG's method. That the so-called peristalsis was nothing but an enhanced rhythmic contraction wave was emphasized in the report published recently8).