A Study on the Cardiac Metabolism by the Method of Coronary Catheterization Part II: the influnces of various cardiac loads

The influence of various loads on the cardiac mctabolism of normal healthy dogs were studied by the method of coronary sinus catheterization that was already described in Part I of this article. Results were as follows: 1) In the cases of the induced want of oxygen, produced by the inhalation of the gas mixture of 10% O_2 and 90% N_2, oxygen (O_2) contents of arterial and coronary sinus blood showed an extreme decrease, and arterio-venous (Q-V) _2 defference diminished remarkably. These datas suggested a considerable decrease of _2 consumption of the heart. Similarly CO_2 contents of arterial and coronary sinus blood showed a decrease, and veno-arterial C_2 difference diminished, suggesting a decrease of CO_2 production of the heart, In respect to A-V difference of the value of blood sugar, no significant changes were generally seen, although in two cases out of six cases, a slight increase was observed. Lactate contents of both the arterial and the coronary sinus blood showed a remarkable increase, but the rate of increase in the case of coronary sinus was higher to such an extent that the value of the lactate of the coronary sinus became exceeded that of the arterial blood. Theses facts suggested the accumulation of lactate in the coronary sinus. It is interesting to note that during short time arter inhalation, A-V difference of lactate showed an increase in a few cases, showing the increased utilization of lactate by the heart. 2) In the cases of the injection of 20 units of the pitressin, O_2 contents of coronary sinus blood showed a decrease, thus suggesting the increased oxygen extraction owing to the reduction of the coronary blood flow. A-V difference of blood sugar showed an increase in most of the experiments. A-V difference of lactate showed a decrease, with an elevation of the value of thie substance in the coronary sinus. 3) In the cases of the experimental arterio-venous fistulas, O_2 contents of coronary sinus blood showed a decrease. A-V difference of the value of blood sugar showed no remarkable changes in most of the cases. In respect to lactate and pyruvate, no definite tendency was seen. 4) In the cases of hemorrhagic shock, O_2 contents of coronary sinus blood showed an increase, and A-V O_2 difference diminished remarkably. A-V difference of the value of blood sugar showed a marked increase, thus suggesting the consumption of blood sugar by the heart. Lactate contents of arterial and coronary sinus blood showed an increase. 5) In the cases of slowly developed heart weakness, O_2 contents of arterial and coronary sinus blood showed a marked decrease, and A-V O_2 difference diminished extremely. A-V difference of the value of blood sugar showed a marked increase. Lactate contents of arterial and coronary sinus blood showed a marked increase, suggesting the increased production of this substance under the anaerobiosis.