| Abstract: | The effects of acetylcholine, subecholine (selective nicotinomimetic) and methylfurmetide (selective muscarinomimetic) on the spontaneous contractions of atrial and ventricular explants from the heart of 408 day embryos as well as of mixed explants, have been studied by means of a special photoelectric device. In most of the experiments, acetylcholine reduced the rate of contractions, the sensitivity of preparations being increased with the age of embryos. Preliminary atropine treatment reversed or significantly decreased acetylcholine effect. Subecholine usually increased the contraction rhythm, whereas methylfurmetide decreased the spontaneous activity. |
