1958 年 78 巻 4 号 p. 341-345
In order to find the substance present in the cardiac muscle that promotes contraction of cardiac muscles, a method for quantitative bioassay was devised using a special apparatus for perfusion of excised heart of a frog (Rana nigromaculata) and frog unit of effective substance was determined. The effective substance was extracted and purified by the method using acetic acid, ether, ethanol and phenol, and a sample with maximum purity of 600U./mg. was obtained, although this substance seemed to contain still some accompanying impurities. The effective substance would not be a homogeneous. The substance responsible for its action is not a protein, is of comparatively low molecular weight, and is extremely easily soluble in water, soluble in dilute ethanol and dilute acetone, but generally insoluble in organic solvents. It is comparatively stable to heat. The substance which accelerates contraction in excised heart of a frog was not the substance that depresses dog's blood pressure that was present in the crude preparation of the former.