Tissue and Blood Acidity

Abstract

In the paper directly following, on tissue acidity, blood acidity and pulmonary ventilation, we studied the problem of respiratory control, by regulating the shift of ions and acid molecules between the blood and tissues. A direct relation between pulmonary ventilation and blood acidity on the administration of carbon dioxide and sodium carbonate, and an inverse relation on the administration of sodium bicarbonate, were demonstrated. These diametrically opposite relationships were harmonized by referring these effects to changes in acidity of the respiratory center itself. Assuming that the acidity of the cerebro-spinal fluid reflected the changes in acidity of the respiratory center, our results agree with the theory that the acidity of the respiratory center is important in the control of pulmonary ventilation. For carbon dioxide turned the cerebro-spinal fluid acid, and increased ventilation; sodium carbonate turned it alkaline and decreased ventilation; and sodium bicarbonate turned it acid, and increased ventilation.

Changes which occur during suspended ventilation offer another approach to the study of tissue acidity, blood acidity and pulmonary ventilation, by virtue of the changes in the coördination of the dual function of hemoglobin. Changes in acidity of the arterial and venous blood of the dog, resulting from mechanical asphyxia, were studied with the continuous method of recording acidity in the circulating blood and with the hydrogen and quinhydrone electrodes. On administering over-ventilation, sufficient to produce apnea, the duration of apnea, and the relation of blood acidity to the end of apnea, were noted. Mechanical asphyxiation, with the lungs filled with either room air or oxygen, permitted partial control of blood acidity and alveolar and blood carbon dioxide pressure.