1. The plasma concentration of hyaluronate (hyaluronic acid; HA) was measured in different vascular beds in order to determine regional kinetics of endogenous HA in fasting, supine subjects with normal (n = 6) or moderately decreased kidney function (n = 9).
2. In both groups hepatic venous HA was significantly below the value obtained in plasma from pulmonary artery, inferior vena cava, and renal veins (P < 0.001), giving a net hepato-splanchnic extraction ratio of HA about 33%.
3. The concentration of HA in renal veins was significantly below that of the pulmonary artery and inferior vena cava (P < 0.05). Average net renal extraction ratio of HA in normal kidneys was approximately 20%. Unilateral kidney function was assessed by 131I-hippuran renography, and the kidney with better function had a significantly higher extraction ratio when compared with the kidney with the lower function (P < 0.025). HA was inversely correlated to glomerular filtration rate (r = − 0.59, P < 0.02).
4. Assuming a plasma flow of 800 and 600 ml/min in normal liver and kidneys, respectively, the average normal plasma clearances of HA in these organs in the resting subject may be estimated to be 250 and 120 ml/min, respectively.
5. The results indicate that the hepato-splanchnic region normally plays a major role in the bio-degradation of endogenous circulating HA. The kidneys also eliminate the compound, presumably the low-molecular-weight fraction of the material. The results may explain abnormally high values of circulating HA in patients with diseases in these organs.