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Background. Portal hypertensive gastropathy (PHG) is a common anomaly with potential for bleeding found in portal hypertension. Blood ammonia levels correlate well with liver disease severity and existence of portosystemic shunts. Increased ammonia results in vasodilation and hepatic stellate cell activation causing and exacerbating portal hypertension. Objective. To assess the relation of blood ammonia to the presence and severity of portal hypertensive gastropathy in cirrhosis. Methods. This cross-sectional study included 381 cirrhotics undergoing screening for esophageal varices (EV) divided into a portal hypertensive gastropathy group (203 patients with EV and PHG), esophageal varix group (41 patients with EV but no PHG), and control group (137 patients with no EV or PHG). A full clinical examination, routine laboratory tests, abdominal ultrasonography, child score calculation, and blood ammonia measurement were performed for all patients. Results. Blood ammonia, portal vein, splenic vein, and splenic longitudinal diameters were significantly higher and platelet counts lower in patients with EV and EV with PHG than controls. Patients having EV with PHG had significantly higher bilirubin and ammonia than those with EV but no PHG. Severe PHG was associated with significantly higher ammonia, EV grades, and superior location and a lower splenic longitudinal diameter than mild PHG. The PHG score showed a positive correlation with blood ammonia and a negative correlation with splenic longitudinal diameter. Conclusions. Blood ammonia levels correlate with the presence, severity, and score of portal hypertensive gastropathy in cirrhosis suggesting a causal relationship and encouraging trials of ammonia-lowering treatments for the management of severe PHG with a tendency to bleed. [ABSTRACT FROM AUTHOR]

It has been proposed that key enzymes of ureagenesis and the alanine aminotransferase activity predominate in periportal hepatocytes. However, ureagenesis from alanine, when measured in the perfused liver, did not show periportal predominance and even the release of the direct products of alanine transformation, lactate and pyruvate, was higher in perivenous cells. An alternative way of analyzing the functional distributions of alanine aminotransferase and the urea cycle along the hepatic acini would be to measure alanine and urea production from precursors such as lactate or pyruvate plus ammonia. In the present work these aspects were investigated in the bivascularly perfused rat liver. The results of the present study confirm that gluconeogenesis and the associated oxygen uptake tend to predominate in the periportal region. Alanine synthesis from lactate and pyruvate plus ammonia, however, predominated in the perivenous region. Furthermore, no predominance of ureagenesis in the periportal region was found, except for conditions of high ammonia concentrations plus oxidizing conditions induced by pyruvate. These observations corroborate the view that data on enzyme activity or expression alone cannot be extrapolated unconditionally to the living cell. The current view of the hepatic ammonia-detoxifying system proposes that the small perivenous fraction of glutamine synthesizing perivenous cells removes a minor fraction of ammonia that escapes from ureagenesis in periportal cells. However, since urea synthesis occurs at high rates in all hepatocytes with the possible exclusion of those cells not possessing carbamoyl-phosphate synthase, it is probable that ureagenesis is equally important as an ammonia-detoxifying mechanism in the perivenous region. [ABSTRACT FROM AUTHOR]