Browsing by Author "CONTRERAS, A"

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    EFFECT OF AGING ON BILIARY LIPID-COMPOSITION AND BILE-ACID METABOLISM IN NORMAL CHILEAN WOMEN
    (1978) VALDIVIESO, V; PALMA, R; WUNKHAUS, R; ANTEZANA, C; SEVERIN, C; CONTRERAS, A
    Biliary lipid composition was determined in fasting gallbladder bile of 12 young and 12 elderly asymptomatic Chilean women with normal weights and recent, normal cholecystograms. The proportion of biliary cholesterol and the lithogenic index were significantly higher in elderly females. Moreover, supersaturated bile was present in 8.3% of the young and in 41.7% of the older women studied. Obesity enhances the saturation of bile in older females: lithogenic bile was found in 100% of 4 elderly, obese women with radiologically normal gallbladders. The bile acid pool and cholic acid metabolism were studied in 5 young and 4 older normal females. Both groups showed similar values of bile acid pool, cholic acid synthesis and turnover. Aging per se modifies the proportions of biliary lipids in Chilean women, and provide a partial explanation for the frequency of gallstones observed among them. The increment in the lithogenic index of gallbladder bile with age takes place without significant changes in bile acid metabolism, suggesting that the canalicular secretion of cholesterol increases with aging.
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    EFFECT OF COMPLETE BILIARY OBSTRUCTION ON BILE-FLOW AND BILE-ACID EXCRETION - POSTCHOLESTATIC CHOLERESIS IN THE RAT
    (1979) ACCATINO, L; CONTRERAS, A; FERNANDEZ, S; QUINTANA, C
    Bile secretory function was studied in rats subjected to a 7-day obstructive cholestasis induced by complete common duct obstruction. Bile flow and bile acid excretion were examined during bile depletion, following the release of the biliary obstruction, and during the infusion of sodium taurocholate at submaximal and saturating rates. A highly significant increase, greater than 100%, in bile flow was evident in cholestatic rats at any bile acid excretory rate when compared to control sham-operated rats. 14C-erythritol clearance measurements performed during bile depletion and during taurocholate infusion suggest that bile flow was mainly of canalicular origin in cholestatic rats. Estimated taurocholate transport maximum (.mu.mol/min per rat) was not statistically different between cholestatic and control rats. Significantly greater taurocholate plasma levels at Tm [maximal excretory capacity] in cholestatic rats suggest a decreased efficiency of the bile acid transport process. The relationship between bile flow and bile acid excretion was nonlinear at low bile acid excretory rates in cholestatic rats. Important changes in bile formation occurred in rats subjected to temporary obstructive cholestatis, which differ from those observed in other models of cholestasis that are associated to a reduction in bile flow and bile acid transport capacity.
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    EFFECTS OF INCREASED BILIARY RESISTANCE ON BILE SECRETION IN THE RAT
    (1984) ACCATINO, L; GAVILAN, P; CONTRERAS, A; QUINTANA, C
    The effects of increased biliary resistance of bile secretion and biliary permeability properties were studied in rats. High biliary resistance produced significant reductions in bile flow and the secretion rate of cholesterol, but did not modify bile salt and phospholipid secretory rates. Decreased bile flow appeared to be secondary to a marked reduction in bile salt-independent fractions of bile flow and bile salt-dependent flow was simultaneously increased. 14C-erythritol and 3H-inulin clearance studies suggest that decreased net canalicular secretion of water rather than increased water reabsorption at the biliary ducts is the mechanism involved in decreased bile flow. In addition, a marked increase in canalicular permeability to inulin was evident when rats were secreting against increased biliary resistance as well as during recovery.
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    THE EFFECT OF COMPLETE BILIARY OBSTRUCTION ON BILE SECRETION - STUDIES ON THE MECHANISMS OF POSTCHOLESTATIC CHOLERESIS IN THE RAT
    (1981) ACCATINO, L; CONTRERAS, A; BERDICHEVSKY, E; QUINTANA, C
    Rats subjected to obstructive cholestasis apparently demonstrate in the postcholestatic period, after common duct obstruction release, a marked increase in canalicular bile flow relative to bile acid excretion. Changes in canalicular permeability and in (Na+-K+)-ATPase activity in isolated liver surface membranes were studied to determine whether they are associated with postcholestatic choleresis. The clearances of 14C-erythritol and 3H-inulin were simultaneously measured in rats subjected to a 3 day obstructive cholestasis and in controls, during spontaneous choleresis as well as during the i.v. infusion of sodium taurocholate at submaximal and saturating rates. In additional groups of bile duct-ligated rats and controls, liver surface membrane fractions were isolated and the activity of appropriate marker enzymes and (Na+-K+)-ATPase was determined. In the 2 groups 14C-erythritol clearance closely approximated total bile flow, suggesting that bile flow was of canalicular origin. Cholestatic rats showed a 6-fold increase in 3H-inulin clearance compared to controls. Canalicular permeability to inulin is apparently markedly increased in cholestatic rats. (Na+-K+)-ATPase activity was significantly higher in cholestatic rats than in controls in the homogenate (P < 0.001) and liver surface membranes, (P < 0.001). Enhanced choleretic response to bile acids in the postcholestatic period is associated with an increased permeability of canalicular structure to inulin and with a significant increase in homogenate and surface membrane (Na+-K+)-ATPase activity. Some important differences between bile secretory function of rats subjected to obstructive cholestasis and that described in models of bile secretory failure induced by drugs or monohydroxy-bile acids, are pointed out.