Intracellular pH and surface pH in skeletal and cardiac muscle measured with a double-barrelled pH microelectrode

The construction of a double-barrelled pH sensitive microelectrode for intracellular use is described. Repetitive measurements of intracellular pH were obtained in rat soleus muscle and sheep Purkinje fibres. They yielded pH values ranging between 7.1 and 7.2 in a CO2/HCO3- buffered medium at 37 degrees C. A lower pH value than that of the bulk solution was found at the surface of the cells using either double-barrelled or single-barrelled pH sensitive microelectrodes.