What does the presence of lactic acid in a sample indicate about what process is occurring?

Salicylic acid products [e.g., Bazuka Extra Strength [26%], Occlusal [26%], Verrugon [50%]] and Salicylic acid/lactic acid combinations [Bazuka, Cuplex, Duofilm, Salactol, Salactac]

Before using a salicylic acid-based product,the affected area should be soaked in warm water and towelled dry. The surface of the wart or verruca should be rubbed with a pumice stone or emery board to remove any hard skin. A few drops of the product should be applied to the lesion, taking care to localise the application to the affected area. The procedure should be repeated daily. Salicylic acid can be recommended to most patients, although diabetics are a notable exception. Salicylic acid does not interact with any medicines. It can cause local skin irritation and, because, of its destructive action should be kept away from unaffected skin.

Lactic Acid

Lactate synthesis is a “necessary evil.” In glycolysis, conversion of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate by glyceraldehyde-3-phosphate dehydrogenase [G3PD] requires reduction of NAD to NADH. The NAD pool is small, and without rapid oxidation of NADH back to NAD, glycolysis would quickly stop at the G3PD step. Extramitochondrial oxidation of NADH back to NAD is accomplished by conversion of pyruvate to lactate via lactate dehydrogenase [LDH]. Since the maximal reported rates of appearance of lactate in blood are only one tenth the FG fiber production rate, it is clear that maximal production rate far exceeds the efflux capacity and that high-intensity exercise must necessarily produce high intramuscular lactate concentration. Intramuscular [lactate] as high as 45–50 mMol/kg of cell water have been reported in man. Intracellular pH in muscle fibers is about 7.0, and decreases 0.4 to 0.8 pH units during intense exercise.

Lactate efflux from muscle occurs mainly by carrier-mediated lactate-proton cotransport and by simple diffusion of undissociated lactic acid. The former probably accounts for 50–90% of the lactate efflux, depending on fiber type and pH. There are three or more muscle lactate transporters. However, Km for lactate has not been found to differ significantly between fiber types, being around 30 mM. The high Km implies that a lot [perhaps most] of the lactate produced will be retained during exercise, regardless of fiber type. Retained lactate maintains an NAD/NADH ratio which stimulates oxidation, and ensures subsequent oxidation or gluconeogenesis in the muscle.

The fate of the lactate produced is primarily oxidative [55–70%], with as much as 90% of the labeled carbon in tracer lactate showing up as CO2 during active recovery from exercise. Lactate released from muscle enters exclusively oxidative tissues in which [lactate] is low [e.g., heart, diaphragm], is converted back to pyruvate and oxidized. Retained lactate is oxidized to generate the ATP needed to replenish phosphocreatine stores following exercise, and to restore normal distribution of Ca2+, Na+, and K+. In liver and kidney, about 5–15% is used for gluconeogenesis and subsequent glycogenesis. The balance is converted to alanine, glutamate, or other substances.

Lactic Acid and Other Markers

Although nonspecific, elevations in CSF lactic acid concentrations [>2.8 mmol/L] are potentially indicative of bacterial meningitis, and lactate may rise prior to the decline in glucose. Normal lactate levels [