The measurement of the activity of urine and serum amylase has been used clinically for almost fifty years. However it became to be known that serum and urine amylase levels may be influenced by conditions with or without pancreas. If we could separate the amylase in isozymes and identify the source of individual isozymes, the mesurement of the levels of amylase will be more reliable index of pancreatic involvement.
Up to 8 isozymes were observed in urine using a simple thin layer polyacrylamide gel electrophoresis suitable for the analysis of amylase isozymes. On the basis of the results of electrophoretic mobility studies, these isozymes migrate similarly to salivary and pancreatic amylase isozyme.
In patients with acute pancreatitis, increased amylase activities were observed on those of pancreatic origin. On the contrary, in patients with pancreatectomy, these isozymes disappeared from urine. In patients with mumps, amylase activities of salivary origin, which were observed in patients with pancreatectomy, increased. From these findings, it was concluded that amylase isozymes in human urine were of pancreatic and salivary origin.
Two major bands and 2 to 4 minor bands were observed in urine of normal subjects. One of the major bands was pancreatic origin, the other was salivary origin. The amylase activity of isozyme of pancreatic origin was greater than that of salivary origin in all of the normal subjects. However, in patients with chronic pancreatitis, the amylase activity of pancreatic origin was less than that of salivary origin.
Pedigree studies indicate that isozyme of Amy U-ls, which migrates slower than the Amy U-l of pancreatic origin, is under autosomal codominant genetic control.
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