Changes in extracellular pH during electrical stimulation of isolated rat vagus nerve

Double-barrelled pH-sensitive micro-electrodes were used to record
changes of extracellular pH during repetitive stimulation of
isolated rat vagus nerves. It was found that a small initial
alkaline shift was followed by a prolonged acidification. The
acidification was correlated in time with the poststimulus
undershoot of the extracellular K+ activity and with the recovery
phase of the nerve conduction velocity. In the presence of ouabain,
the acid component of the pH change was completely abolished
(indicating a metabolic origin), whereas the alkaline component
remained unaltered. These pH changes were too small to make a
significant contribution to the activity-related changes in
conduction velocity of the vagal C-fibres.