A NEW APPROACH TO THE ASSESSMENT OF ANAEROBIC METABOLISM - MEASUREMENT OF LACTATE IN SALIVA

Objective-To test the hypothesis that saliva lactate concentrations ma y reflect those present in blood and that saliva lactate can be used a s a very convenient and useful variable in the study of anaerobic meta bolism. Methods-Parallel determinations were made of lactate in saliva and in capillary blood samples, obtained at 3 min intervals from nine individuals during the performance of a maximum graded exercise test on a cycle ergometer against increasing workloads (from 25 up to a max imum of 300 W). Lactate determinations were done by means of an electr oenzymatic method using 25 yl samples in both types of fluids. Results -For each situation, the concentration of lactate in saliva was shown to be about 15% of that in plasma but it followed the same pattern of evolution during the exercise test. A good correlation (r = 0.81) betw een blood and saliva lactate concentrations was found. The precision o f the method was very good, with a coefficient of variation ranging (n = 10) between 2.2% for samples with very low lactate concentrations a nd 0.7% for sample with moderate lactate concentrations. Lactate appea red to be very stable in saliva over a period of 40 days after collect ion, when kept at 4 degrees C. The values obtained after this period w ere virtually identical to those shown in fresh samples. Conclusions-D etermination of lactate in saliva can be used as an alternative to det ermination in blood, overcoming most of the drawbacks of the procedure s being used at present, since the collection of the samples required no special expertise.