Hyaluronan is a structural component of the interstitial matrix in skin and is catabolized locally in skin as well as by lymphatic removal and subsequent degradation in lymph nodes and liver. The present experiments were designed to evaluate the role of interstitial fluid flux in turnover of hyaluronan in skin by measuring the maximal lymphatic flux of hyaluronan. Lymph flow, total protein concentration, hyaluronan concentration, and flux were measured every 15 min in prenodal lymph from the hind paw in 12 pentobarbital-anesthetized mongrel dogs at normal and increased interstitial fluid flux. An intravenous saline load (15% of body weight during the course of 30 min) was followed by a one-step increase in local venous pressure 30 min later (to a maximum of 50 mm Hg) and maintained at this level for the next 240 min. Lymph flow and hyaluronan concentration during the control period averaged 25.6 ± (SD) 23.2 (range 4.7-61.9) μl/min and 8.6 ± 2.8 (range 2.0-11.6) μg/ml, respectively. The hyaluronan concentration fell by 30% during the experimental period, while the lymph flow increased up to ten times above control. Total tissue water increased from 1.73 ± 0.11 ml/g dry weight during the control period to 1.91 ± 0.12 ml/g dry weight at the end of the experiment (p 0.05). The average lymphatic hyaluronan flux was 8.4 ± 5.4μg/h during the control period, peaked at about 60 μg/h, and averaged 33.6 ± 13.9 μg/h during the last hour of the experimental period. The total amount of hyaluronan drained from the paw during the 5-hour experimental period averaged 182 ± 137 (range 39-525) μg and corresponds to the normal daily lymphatic output of hyaluronan. Thus, the hyaluronan flux in lymph increases with increasing lymph flow and is maintained over a period of several hours, affecting hyaluronan tu