Membrane lipid changes in erythrocytes, liver and kidney in acute and chronic experimental liver disease in rats.

Lipid molecules in lipoprotein surfaces exchange with their counterparts in cell plasma membranes. In human or experimental liver disease, plasma lipoprotein surfaces are enriched in cholesterol and deficient in arachidonate; corresponding alterations occur in membrane lipids of erythrocytes. To determine whether similar changes take place in membranes of nucleated cells, the lipid content of plasma and of erythrocyte, liver and kidney membranes was measured in rats with acute (3-day) galactosamine-induced hepatitis or chronic (3-week) biliary obstruction. In both models of liver injury the cholesterol:phospholipid ratio in plasma and in erythrocytes was significantly increased (P less than 0.001). Although this ratio was also elevated in liver and kidney microsomes, only in liver microsomes of obstructed rats was the increase significant (P less than 0.001). However, the cholesterol:phospholipid ratio of kidney brush-border membranes, was significantly higher in bile-duct-ligated rats; presumably, compensating mechanisms limit cholesterol accumulation in intracellular membranes. Kidney brush-border membranes from obstructed rats were deficient in arachidonate as were plasma and erythrocytes. However, arachidonate levels were unchanged in kidney microsomes; renal delta 6-desaturase, the rate-limiting enzyme in the conversion of linoleic acid to arachidonic acid, was increased by 50% (P less than 0.001) and may have counteracted a reduced supply of exogenous lipoprotein arachidonate. We conclude that in experimental liver disease lipoprotein-induced lipid abnormalities can occur in renal membranes, although compensatory mechanisms may operate; the alterations seen, cholesterol accumulation and arachidonate depletion, would be expected to interfere with sodium transport and prostaglandin production, respectively. Our findings support the hypothesis that lipid abnormalities in kidney membranes contribute to the renal dysfunction which is a frequent complication of human liver disease.

Enhancement of the urinary excretion of non-sulphated and sulphated radioactive bile acids by sodium acetate in the bile duct obstructed rat.

The renal clearances of [14C]glycocholate, [14C]taurocholate and [3H]glycochenodeoxycholate-3-sulphate were determined in bile duct obstructed rats. Comparisons of the bile acid clearances with glomerular filtration rates (GFR) indicate that most of the filtered bile acids are reabsorbed. Inhibition studies with p-aminohippurate (PAH) and probenecid suggest that a proportion of the bile acids in urine is secreted. Attempts were made to increase the renal clearance of the bile acids by the administration of pharmacological agents. An infusion of sodium acetate (0.3 mol/l) increased the clearance of the radioactive bile acids and augmented the urinary excretion of endogenous 3 alpha-hydroxy bile acids and reduced their concentration in plasma.

Changes in the binding of radioactive conjugated bile salts to serum proteins in cholestatic jaundice.

1. A micro-partition centrifugal ultrafiltration technique has been used to monitor the percentage of [14C]glycocholate, [3H]glycochenodeoxycholate and [3H]glycochenodeoxycholate-3-sulphate bound to serum proteins of patients with cholestatic liver disease. 2. In comparison with normal individuals the percentage of binding of [14C]glycocholate and, to a lesser extent, of [3H]glycochenodeoxycholate and [3H]glycochenodeoxycholate-3-sulphate was reduced. 3. The binding of [14C]glycocholate was inversely related to the serum bile salt and bilirubin concentrations. In contrast, the binding of [3H]glycochenodeoxycholate and [3H]glycochenodeoxycholate-3-sulphate were not altered by the severity of the cholestasis. 4. Studies in vitro indicated that the reduction in the binding of [14C]glycocholate in cholestatic liver disease was not due to high concentrations of bile salts, unconjugated bilirubin or fatty acids.

A distinctive pattern of serum bile acid and bilirubin concentrations in benign recurrent intrahepatic cholestasis.

The pattern of serial serum bile acid and bilirubin concentrations in 3 patients with benign recurrent intrahepatic cholestasis (BRIC) was compared with those from patients with other liver diseases. In BRIC the peak bile acid concentration (260- 575 micromol/l was found at the onset of the cholestasis. The bilirubin concentration increased slowly so that maximum values (185-550 micromol/l) were attained between 33 and 51 days after the onset of symptoms. Both the serum bile acid and bilirubin concentrations returned to normal after 79 to 98 days. Percutaneous biliary drainage of extrahepatic biliary obstruction (3) caused a dramatic reduction in the serum bile acid level (mean 89% after 48 hours), but only a slight fall in serum bilirubin (mean 22%). In primary biliary cirrhosis (2) the bile acid and bilirubin concentrations changed in parallel until the onset of liver failure when serum bilirubin, but not bile acids, increased markedly. Serum bile acid and bilirubin concentrations changed in parallel throughout cholestatic viral hepatitis (2), chronic active hepatitis (2) and alcoholic hepatitis (1). The data indicates that a distinctive pattern is found in BRIC and this may be of diagnostic value.

A direct fluoroimmunoassay for conjugated chenodeoxycholic acid using antibody coupling to magnetisable particles.

A novel solid phase fluoroimmunoassay for conjugated chenodeoxycholic acid has been developed employing an antiserum coupled to magnetisable cellulose particles and a chenodeoxycholyl glycinefluorescein thiocarbamyl ethylene diamine conjugate as the label. The data obtained from serum samples from 25 patients correlated closely (r = 0.99) with those obtained by radioimmunoassay. The assay is rapid (30 minutes), simple, and ideal for routine clinical purposes.

The detection of minimal alcoholic liver disease by three methods.

The serum aspartate transaminase, 2-h post-prandial bile acids and the aminopyrine breath test were measured in 14 alcoholics with histologically proved minimal liver damage. A raised aspartate transaminase value was found in 64% (9/14) of the patients and was the commonest abnormality found. In three patients all three tests were normal. Six patients stopped abusing alcohol and, when reassessed a mean of 33 days later, showed significant changes in the mean aspartate transaminase value and the mean value for the aminopyrine breath test. There was no significant change in the mean post-prandial bile acids value. The remaining eight patients continued to drink alcohol and, when reassessed at a mean of 118 days, showed no significant change in any of these indices. Of the methods assessed, the serum aspartate transaminase appeared to be the most useful for detecting and monitoring patients with minimal alcoholic liver disease. However, all three tests failed to detect an unacceptably high percentage of the patients, and liver biopsy therefore remains a more certain diagnostic method.

Assessment of the plasma disappearance of cholyl'l14C-glycine as a test of hepatocellular disease.

The plasma disappearance of a tracer dose of cholyl-l14C-glycine has been examined in 12 control subjects and in 32 patients with hepatocellular dysfunction. Simple analysis of the data did not detect hepatic dysfunction except in severe hepatocellular disease. The greatest degree of discrimination between normal subjects and patients with mild liver disease was obtained by taking the ratio of the plasma retention at 60 minutes to that at 10 minutes; it was similar to that obtained with serum gamma-glutamyl transferase. The two hour post-prandial plasma "total" bile acid concentration gave complete separation between the control subjects and patients with liver disease.

A simplified procedure for the isolation of bile acids from serum based on a batch extraction with the non-ionic resin--Amberlite XAD-7.

A simple and reproducible method using the non-ionic resin, Amberlite XAD-7, for the isolation of bile acids from serum by a batch procedure is described. Recoveries were greater than 95% for the non-sulphated bile acids and greater than 70% for the sulphate esters of bile acids. By using 1 g of resin, recoveries were independent of the mass (0.1-5 mumol) of the bile acid present. Up to 35 samples a day can be extracted without requiring dedication of the operator. When serum extracts were analysed by the 3alpha-hydroxysteroid dehydrogenase procedure for estimation of bile acids, virtually all the background fluorescence was eliminated. These extracts were also suitable for gas liquid chromatography, thin layer chromatography, and radioimmunoassay.