Importance of the lactate anion in control of breathing

The purpose of this study was to examine the effects of raising the arterial La- and K+ levels on minute ventilation (((V) over dot E)) in rats. Either La- or KCl solutions were infused in anesthetized spontaneously breathing Wistar rats to raise the respective ion arterial concentration ([La-] and [K+]) gradually to levels similar to those observed during strenuous exercise. (V) over dot E, blood pressure, and heart rate were recorded continuously, and arterial [La-], [K+], pH, and blood gases were repeatedly measured from blood samples. To prevent changes in pH during the La- infusions, a solution of sodium lactate and lactic acid was used. Raising [La-] to 13.2 +/- 0.6 (SE) mM induced a 47.0 +/- 4.0% increase in (V) over dot E without any concomitant changes in either pH or PCO2. Raising [K+] to 7.8 +/- 0.11 mM resulted in a 20.3 +/- 5.28% increase in ire without changes in pH. Thus our results show that La- itself, apart from lactic acidosis, may be important in increasing (V) over dot E during strenuous exercise, and we confirm earlier results regarding the role of arterial [K+] in the control of (V) over dot E during exercise.