Changes in skeletal muscle cell pH during graded changes in PCO2

Blood perfusing isolated dog gracilis muscles was equilibrated with CO2 tensions ranging from 30 to 120 mm Hg, resulting in venous P CO2 from 35 to 135 mm Hg. Extracellular pH values ranged from 6.96 to 7.41, and muscle cell pH, calculated from DMO distribution, ranged from 6.64 to 6.94. When intracellular pH was plotted as a function of the corresponding extracellular pH, a linear relationship (r = 0.92) was observed throughout the entire pH range. The slope deltapHi/deltapHe was 0.64, without evidence of a difference in slope at different pH values. These results do not support the previous observations in rat diaphragms that cell pH is not affected by PCO2 changes over a certain extracellular pH range. pHe was 0.64, without evidence of a difference in slope at different pH values. Theses results do not support the previous observations in rat diaphragms that cell pH is not affected by PCO2 changes over a certain extracellular pH range.