體外培養組織に於けるAcetylcholinの分解に就て

Abstract

Y. Nakazawa has previously reported that acetylcholine was decomposed by the tissues of the chick embryo cultured, in vitro. In order to study more precisely, the tissue-slices of heart and liver of the chick embryo were cultivated, in a medium in Carrel's battles. Acetylcholine (ACh) was added to and the amount of undecomposed ACh after 18, 24 or 48 hours from the beginning was estimated biologically using frog's rectus abdominis. Results : ACh was decomposed not only by the heart-and liver tissues but also by the culture me dium itself which was made from the extract of the chick-embryo. So these tissue-slices wese cultured in vitro only with Ringer's solution as their nutrient source. No decomposition of ACh was observed in the cultured tissues, the growth of which have been checked by addition of As2O3. The decomposition of ACh by the cultured tissues was suppressed by the simultaneous presence of caffeine, vagostigmine, procaine, and physostigmine. The degree of suppression of ACh decomposition by caffeine was a little stronger in the heart tissue culture than in the liver culture, but it was just the opposite in the case of vagostigmine as well as of procaine. ACh when added in large amount together with physostigmine to the medium was decomposed more by the heart tissue than by the liver, but in the case of a small amount of ACh the condition was reversed. From the results it is concluded that ACh is decomposed by cholinesterase (ChE) inherently contained in these tissue-slices, and that the liver of the chick-embryo contains more true ChE than the heart, but the latter is more rich in the pseudo-ChE contents than the former.