Local myocardial blood-flow measured by the use of a needle-type Pt-H2 electrode.

In order to measure local myocardial blood flow respectively, a needle-type recessed Pt electrode sealed in a thin injection needle was constructed. By means of this electrode, the myocardial blood flow in the inner and outer portions of the anterior wall of the exposed left ventricle of anesthesized dogs was studied. Under conditions, the blood flow in the inner portion (112.4 ml/100 ml/min) exceeded that in the outer portion (98.7 ml/100 ml/min). But the blood flow distribution expressed in terms of the blood flow ratio in both portions was readily varied by several pharmacological treatments, starvation, or prolongation of the experiment. Combining these observations with the results obtained in the decrease of the O2 current in the coronary occlusion test, the following possibilities seemed probable: 1) The myocardial blood flow under normal conditions was so distributed that the inner layer could be supplied with an increased blood flow and more oxygen. 2) Such a balance between the local blood flow and O2 demand can often be disturbed under various conditions, as was seen in the case of isoproterinol infusion in the present study.