Renal handling of amylase. Renal tubular reabsorption of salivary-type isoamylase.:Renal Tubular Reabsorption of Salivary-Type Isoamylase

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The renal tubular reabsorption of amylase was studied in 7 healthy volunteers by measuring urinary excretion of amylase and determing isoamylase pattern before and during inhibition of tubular reabsorption by a 20-minutes infusion of arginine at a rate of 0.6g/min. The excretion of amylase was compared with that of beta-2-microglobulin. The excretion of beta-2-microglobulin rose from a mean baseline excretion of 0.14±0.08μg/min to a peak of 18.63±2.72μg/min, a 137-fold increase. The maximal values were found during infusion of arginine in all cases. The excretion of amylase rose from a mean basal excretion of 3.90±0.32 Somogyi Unit (SU)/min to a mean peak value of 8.33±1.33SU/min during arginine infusion, a 2.1-fold increase. These results indicate that amylase is reabsorbed in the tubular cells, but only a very modest degree compared to beta-2-microglobulin. Amylase isoenzyme analysis revealed that the elevation of urinary amylase excretion was mainly due to an increase of salivary-type isoamylase activity. Thus, the ratio of pancreatic to salivary-type isoamylase in urine decreased during arginine infusion, a clear indication of tubular reabsorption of salivary-type isoamylase. The present study suggests that the high tubular reabsorption of salivary-type isoamylase contributes to the high renal clearance of pancreatic-type isoamylase compared to that of salivary-type isoamylase.
財団法人日本消化器病学会の論文