Mean whole body intracellular pH in unanesthetized dogs: A revised method

Abstract

An improved method of calculating the mean whole body intracellular pH (pHī) by means of DMO in unanesthetized dogs is described. The elimination of DMO from the body fluid is assumed to follow a simple exponential decay with a time constant k 1. The distribution of DMO into the extracellular and intracellular water is described by an exponential function (1−exp(− k 2 t)). From experiments in 9 unanesthetized dogs it was found that k 1 = 0.008 h −1 and k 2 = 1.325 h −1. Mean pHi was 7.08 ± 0.05 at Pa CO 2 = 4.1 kPa (31 mm Hg). The average difference between arterial blood and pHī was 0.35. No statistically different pHT values were found with data from arterial or mixed venous blood. Even after 24 h the method still yields reasonable values for pHī.