Age-dependent variations in white adipose tissue glycerol and lactate production after surgery measured by microdialysis in neonates and children

In previous studies, we observed that lactate concentrations in interstitia l white adipose tissue are higher in small infants than in adults. Moreover , no lipolysis following catecholamine challenge has been reported in neona tes and small infants. Our aim was to determine with microdialysis whether the above mentioned age-dependent changes could be detected in situ after s urgery. A microdialysis catheter was introduced into the abdominal subcutan eous tissue in 13 neonates and 12 children undergoing surgery. Interstitial concentrations of glucose, lactate and glycerol were measured hourly durin g the first 20 postoperative hours. The concentrations of lactate in inters titial white adipose tissue were consistently higher in neonates compared t o older children, with a significant difference during the 9-18 h postopera tive period (P < 0.05). A significant difference in the lactate:glucose rat io was observed at 1-2, 8-10, 15 and 18 h postoperatively (P < 0.05). No si gnificant differences were observed between the two groups with respect to glycerol and glucose concentrations. Interstitial lactate concentrations in white adipose tissue were higher in neonates compared with children in the early postoperative period. No age-dependent difference in postoperative l ipolysis, measured as interstitial glycerol concentrations, was observed. T hus, an age-dependent difference in interstitial lactate production, but no t lipolysis, was detected in the early postoperative period.