Continuous recording changes in hydrogen ion concentration of circulating blood

Abstract

In the study of the chemical regulation of respiration a need for a continuous method of recording changes in the hydrogen ion concentration of the circulating arterial and venous blood was felt. Such a method has been developed.

By means of a specially devised electrode vessel, a manganese dioxide electrode was placed in the circulating blood. The chain was closed with a non-polarizable electrode, and the E. M. F. recorded potentiometrically on smoked paper by means of a writing point attached to the hard rubber drum of a Leeds and Nor-thrup type K potentiometer.

The continuity of the method, the facility of recording changes in C_H+, the amount of data obtainable from single animals, and the possibility of recording synchronous changes in C_H+ in the arterial and venous blood along with changes in pulmonary ventilation, oxygen consumption, blood pressure, etc., are advantages which make the method extremely valuable. In experiments so far performed the method has shown characteristic changes in the C_H+ of the blood with various procedures.

The administration of CO₂ eliciting increased pulmonary ventilation was accompanied by a sharp rise in the C_H+ of the arterial blood, followed by a slower fall in C_H+ during recovery.

The intravenous injection of NaHCO₃, produced a sudden fall in the C_H+ of the arterial blood, followed by a slow return to normal. Though the changes in C_H+ were large they were unaccompanied by changes in pulmonary ventilation. See Figure 1.

Occlusion and de-occlusion of the trachea produced typical changes in blood pressure and respiration. The C_H+ record resembled in detail the form of the blood pressure record. A record of such an experiment is shown in Figure 2.

The administration of rarefied air eliciting increased pulmonary ventilation was accompanied by a decrease in the C_H+ of the arterial blood. Subsequent administration of room air was followed by a further short but sudden decrease in C_H+, giving way to an increased C_H+.