Increased Tissue Lactate Concentration in Incision Models

초록

Background : It is well known that increased lactate is present in wounds. The increase in lactate is not necessarily caused by a limitation of oxygen delivery and may not primarily indicate ischemia. In this study, we measured the time course of the changes in lactate produced in incisions at 3 different sites (hindpaw, gastrocnemius m., back) in order to figure out factors that may activate and sensitize nociceptors in the incision. Methods : Incisions were performed in each sites (a plantar, a gastrocnemius muscle or paraspinal). Others received a sham incision. A microdialysis fiber was passed into the subcutaneous tissue of the plantar aspect of the hindpaw or paraspinal area or the gastrocnemius muscle.5 different concentration of lactate were used in the perfusate and were applied serially in increasing concentration at flow rate 2.5 l/min for 40 min equilibration and collected samples for another 15 min. The uninjured sites were used for control and both sites were perfused at the same time. Then tissus lactates were measured at 0, 1, 2, 4, 7, 10, 14 days in hindpaw or 0,1,2,4,7,10 days in gastrocnemius m., or 0, 1, 2, 4, 8, 14 days in paraspinal area after incisions. Results : In hindpaw, tissue lactate was increased on the day of incision and on POD 1 through 7. It was not different than the control paw on days 10 and 14. In the gastrocnemius muscle, lactate was increased on POD 1 through 4 and paraspinal lactate also was increased on the day of incision and on POD 1 through 8 and normalized on POD 14. Conclusion : These data suggest that tissue lactate was increased after incisions and it was in part parallel to pH and the pain behaviors caused by the incisions. Together, these mediators may contribute to incisional pain.