Markedly increased lymphatic removal of hyaluronan from skin after major thermal injury

Hyaluronan (HYA) (formerly hyaluronic acid) is an important constituent of the interstitial matrix in skin. Following major burn injury plasma HYA is known to increase markedly. The present study investigated to what extent the lymphatic removal of HYA from skin is affected following major burn injuries. Under ketamine anaesthesia a 30 per cent full thickness scald injury was inflicted on sheep previously provided with a chronic prefemoral lymph fistula. Animals were resuscitated for 24 h using lactated Ringerʹs infusion as needed to restore and maintain cardiac output within ± 10 per cent of baseline. Following burn injury, lymph flow from thermally injured tissue gradually increased to 10–25 times above baseline. The baseline HYA concentration in lymph was 4.3 ± 1.1 μg/ml; the HYA concentration in lymph was not significantly altered postinjury. The lymphatic HYA flux (flow × concentration) increased postinjury to 5–30 times control. The HYA concentration in plasma was 162 ± 12 ng/ml at baseline; postinjury plasma HYA peaked at two to three times baseline at 4–8 h after the injury. At 24 h postinjury plasma HYA was reduced compared to baseline. In conclusion, after major burn injury the lymphatic transport of HYA from the injured area into the systemic circulation increased markedly, leading to elevated plasma concentrations of this high molecular weight connective tissue component.