LACTATE CLAMP - A METHOD TO MEASURE LACTATE UTILIZATION IN-VIVO

A lactate clamp method has been developed to quantify the whole body l actate utilization in conscious, unstressed rats. Dichloroacetate (DCA ), a known lactate utilization enhancer, was used to validate the meth od. Fasting blood lactate concentrations before the clamps were identi cal for DCA-treated(1 mmol/kg) and control groups (1.65 +/- 0.37 vs. 1 .65 +/- 0.19 mM). The animals received a primed continuous lactate inf usion for 90 min at variable rates to clamp the blood lactate concentr ation at 2 mM. The steady-state (60-90 min) lactate infusion rate, whi ch represents the whole body lactate utilization in DCA-treated animal s, was 144% higher than that in the control animals (13.2 +/- 1.0 vs. 5.4 +/- 1.1 mg.kg(-1).min; P < 0.001). The markedly increased lactate infusion rate indicates an enhanced lactate flux by DCA. To determine whether the increased lactate infusion by DCA reflected reduced endoge nous lactate production, lactate production was measured. The results indicate that endogenous lactate production was not affected by DCA. I n conclusion, the lactate clamp provides a sensitive and reliable meth od to assess lactate utilization in vivo, a dynamic measurement that m ay not be clearly demonstrated by blood lactate concentrations per se.