Alkaline Phosphatase in Experimental Biliary Cirrhosis

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Abstract
The histochemical distribution of alkaline phosphatase in the liver was detd. in dogs that survived exptl. biliary obstruction for 44-291 days. There occurred considerable dilatation and tortuosity of bile capillaries with accumulation of phosphatase not only in the lumens but also around the bile capillaries and in the cytoplasm of parenchymal cells. The changes were similar in all the livers studied and the serum phosphatase was uniformly considerably increased. In the rabbit there likewise occurred dilatation of bile capillaries but here there was little accumulation of phosphatase about the bile canaliculi and there was no significant retention of the enzyme in the cytoplasm. Cirrhotic changes occurred early and were extensive. The histo-chemically demonstrable phosphatase activity was similar in all livers of animals that survived 4-31 days, regardless of whether the alkaline phosphatase in the blood remained moderately elevated or returned to the normal level. The rise of urinary phosphatase excretion was too inconsistent to account alone for the moderate increase of blood phosphatase in this species as compared with the marked increase in the dog. Alkaline phosphatase activity outlined the bile capillaries in an almost selective manner. The changes seen after biliary obstruction did not indicate that true breaks occurred in the continuity of the biliary system which would account for the regurgitation of bile in obstructive jaundice. The demonstrable distribution of alkaline phosphatase activity in conjunction with the blood phosphatase levels following biliary obstruction suggest that the role of the liver is primarily that of a regulatory organ concerned with the excretion of surplus phosphatase. Further exptl. evidence recorded in the recent literature supports this opinion.