Circulating hyaluronate: concentration in different vascular beds in man.

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). In both groups hepatic venous HA was significantly below the value obtained in plasma from pulmonary artery, inferior vena cava, and renal veins (P less than 0.001), giving a net hepato-splanchnic extraction ratio of HA about 33%. The concentration of HA in renal veins was significantly below that of the pulmonary artery and inferior vena cava (P less than 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 less than 0.025). HA was inversely correlated to glomerular filtration rate (r = -0.59, P less than 0.02). 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. The results indicate that the hepato-splanchnic region normally plays a major role in the biodegradation 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.