Regulation of urea synthesis by diet protein and carbohydrate in normal man and in patients with cirrhosis. Relationship to glucagon and insulin

摘要: Diet protein increases whereas carbohydrates decrease urea synthesis. Traditionally, these effects have been explained by changes in substrate supply. intake carbohydrate decreases blood amino acid concentration. However, glucose also synthesis a hepatic mechanism independent of the Whether this is due to an effect itself, or whether fall glucagon rise insulin responsible, was not known. This survey deals with increase diet and separate glucose, on functional nitrogen clearance normal man patients cirrhosis liver. The calculated as slope linear regression analysis alanine-stimulated rate alpha-amino concentration, expresses In cirrhosis, reduced parallel liver cell mass, despite high concentration that would normally up-regulate process. both healthy subjects (plus approximately 50 g/day) for 14 days 40%. Thus, addition effect, liver, probably enzyme formation. What induces clear but postprandial levels may be involved. Although qualitatively intact patients, response relative two-thirds. important control during partly explain why usually tolerates hyperalimentation without developing encephalopathy. It shown reduction depends hyperglycaemia, accomplished additive direct hormone-independent action indirectly via suppression glucagon. Insulin controller clearance, still considered regulator its reducing High experimental overrule suppressive glucose. contrast, it sugar-alcohol xylitol normalises induced clearance. During exerts only very little does down-regulate when spontaneous are normalised somatostatin, shows intact. These findings indicate hormone responses Incomplete secretion alanine infusion contributes levels. removal itself. hyperglucagonaemia compensatory which cirrhotic some extent reestablishes capacity produce urea. consequence defective down-regulation i.e. sparing two different mechanisms: A component (reduction clearance) peripheral (reduced availability mediated response). extension former thoughts according reduces solely