抄録
In the previous report, the author pointed out the fact that the graphic records and the minute volume of outflow of an isolated toad's heart, perfused by the author's method and observed for several hours or even longer without interruption, could be divided into three periods. The measurement of criteria in the electro- and mechanograms (EG and MG) revealed that there was an equilibrium in the graphic records in the middle period of perfusion, and, at the same time, the minute volume of outflow suggested that the cardiac activity was rather stationary during this period. In order to ascertain the internal stability of the above mentioned equilibrium in the graphic records or the stationary state of activity, the author tried to alter one of the conditions of perfusion, such as the temperature of fluid, the pressure of inflow or the ionic contents. By means of these tests, a certain definite reaction of the isolated heart against the altered condition was observed in each case, and every reaction of this kind was found to be reversible. The reversibility was most perfectly maintained in the middle period during which the previous state of equilibrium ought to be restored within 20 minutes. On the other hand, the height and the duration of ventricular complex of EG were compared respectively with those of ventricular MG, and it was found that both graphic records changed usually in one and the same direction against the moderate alteration of the condition of perfusion. This type of parallelism was again moat evidently maintained during the middle period. By this reversibility in the reaction and parallelism between EG and MG, the author is convinced of the stability of the equilibrium in the middle period. Hence, this period observed by the present method of perfusion is most reliable in reproducing the experimental results accurately.
