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Free keywords:
Pancreas; Acini; Ducts; Membrane Enzymes
Abstract:
Enzymes activities of the Na+K+-and the HCO3−-ATPases, alkaline phosphatase, amino peptidase and 5′ nucleotidase have been measured in 4 different preparations from the cat pancreas a) in the ducts including all sizes b) in ducts of three different diameters c) in that tissue, which had been dissected off from the ducts, called “acini”, and d) in the whole homogenate of the pancreas. The distribution of the measured enzymes shows, that the Na+K+-activity is highest in the acinar structures (mean value 0.532 μM/mg Protein x h), while the ducts show nearly no Na+K+-ATPase activity. The HCO3−-ATPase, the alkaline phosphatase and the 5′ nucleotidase are in the ducts between 2.4 and 3.6 times higher than in the whole organ whereas the amino peptidase does not appear to have a selective distribution. As the HCO3−-ATPase activity distribution pattern is identical with that of the secretory capacity of HCO3− as evidenced by earlier micropuncture studies, the data suggest that the HCO3−-ATPase is the main enzyme involved in the secretion of the bicarbonate buffer. Concerning the Na+K+-ATPase activity in the acinar structures we cannot contribute to its function in the enzyme secreting process.
