The DC Potential between CSF and Plasma in Respiratory Acidosis

Abstract The electrical DC potential between cisternal cerebrospinal fluid and jugular venous blood was measured in rats during respiratory acidosis and alkalosis. In one of the main series studied, respiratory acidosis and alkalosis was upheld for 5, 15, 45 and 180 min in animals anesthetized with nitrous oxide. In the other main series, sustained hypercapnia was induced by exposing unanesthetized rats to about 5 or about 11% CO2 for 3, 24 and 48 h, respectively. In this series, the animals were anesthetized during the last 30–45 min of the hypercapnia. In acute respiratory acidosis and alkalosis, the CSF‐plasma potential difference varied linearly with the plasma pH with a slope of about ‐27 mV/pH unit. The CSF‐plasma potential differences measured in sustained hypercapnia did not deviate significantly from the mean regression line calculated from the acute experiments. The results thus showed that the CSF‐plasma potential difference was not only increased during acute respiratory acidosis, but also remained increased as long as the plasma pH was acid.