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We demonstrated pulmonary arteriolar blood flow-mediated CO2 gas excretion in rabbit lungs. The shear stress stimulation produced CO2 gas in cultured human endothelial cells of pulmonary arterioles via the activation of F1/Fo ATP synthase. To confirm the findings in human subjects undergoing the operation with heart–lung machines, we aimed to evaluate the effects of a stepwise switch, from a partial to a complete cardiopulmonary bypass, of the circulatory blood volume (BV, 100% = 2.4 × cardiac index), on the end-expiratory CO2 pressure (PetCO2), maximal flow velocity in the pulmonary artery (Max Vp), the inner diameter (ID) of pulmonary artery, pulmonary arterial CO2 pressure (P mix v CO2), pulmonary arterial O2 pressure (P mix v O2), hematocrit (Hct), pH, the concentration of HCO3−, and base excess (BE) in mixed venous blood in 9 patients with a mean age of 72.3 ± 3.4 years. In addition, the effects of the decrease in Hct infused with physiological saline solution (PSS) on PetCO2 were investigated in the human subjects. An approximately linear relationship between the PetCO2 and Max Vp was observed. The pumping out of 100% BV produced little or no change in the Hct, pH, P mix v CO2, and P mix v O2, respectively. The hemodilution produced by intravenous infusion of PSS caused a significant decrease in the Hct, but not in the PetCO2. In conclusion, another route of CO2 gas excretion, independent of red blood cells, may be involved in human lungs.

A misfire phenomenon taking place in a discharge circuit composed of a capacitor and thyristor has been investigated. This circuit was operated at a frequency of up to 198 Hz. A misfire was observed in a circuit with a PET capacitor at low temperatures, while no misfire was observed with a PP capacitor under any conditions. Transient currents in the range of 40 A to 1 mA were measured with a digital oscilloscope. In the case of a PET capacitor, the current initially decreased exponentially at a given time constant, but exhibited a slow decay which caused the misfire. This current is associated with residual charges trapped in the bulk of the PET film. © 2001 Scripta Technica, Electr Eng Jpn, 137(2): 1–7, 2001