Studies of fetal and neonatal isolated guinea pig lung on the effect of electric tissue resistance on the ECG

The results of measurements of the electrical resistance of lung tissue are reported in order to estimate quantitatively the influence of air and blood filling on the conductivity. Experiments were done on isolated lung tissue of fetal and infantile guinea pigs. The ohmic resistance was measured by a minimised 4-electrode technique: isolated fetal lungs empty of air, or artificially aerated ones on the one hand, isolated lungs of infantile animals with spontaneous respiration and normal lung blood flow on the other hand. The increase of the electrical resistance produced by aeration is reduced by at least 50% by the synchronously increasing blood flow in spontaneously respired lungs. These experiments in the described animal model offer an opportunity for a more precise interpretation of the electrocardiogram of human adults changing with respiratory phases.