Abstract #1689

Hrovat M, LaRaia A, Farrar C, Lewis G, Pappagianopoulos P, Systrom D

31P magnetic resonance spectroscopy (MRS) is used to measure intracellular pH (pHi) during exercise. The decreased pHi observed during exercise is correlated with measures of increased ventilatory drive even under conditions that restrict possible vascular mediated chemical signaling of central neural circuits. This suggests that skeletal muscle hydrogen ion concentration stimulates ventilatory drive in the normal human through direct neural pathways during exercise. This is in contrast to previous models of ventilatory control where arterial chemoreceptors were argued to be stimulated by increased blood concentrations of metabolites such as lactic acid.