109
Archives Internationales de Physiologie, de Biochimie et de Biophysique, 1992, 100, 109-111
R e g le 29 janvier 1991.
Changes in microsomal phospholipid fatty acids composition in cholestatic rats BY
L. A. BENGOCHEA, C. B. OUVIRA, A. PAVESE and A. LEMBERG (Catedra de Fisiopatologia, Facultad de Farmacia y Bioquimica, Universidad de Buenos Aires)
Archives of Physiology and Biochemistry Downloaded from informahealthcare.com by Chulalongkorn University on 12/29/14 For personal use only.
(1 figure)
In the rat, the effect of the bile duct ligation on liver microsomal phospholipid fatty acid composition and on phosphatidylcholine, phosphatidylserine and phosphatidylinositol pattern were studied. After two days of cholestasis, microsomal phospholipid fatty acids showed a decrease in linoleic, stearic and arachidonic acids and an increase in oleic and docosahexaenoic ones, as compared to controls. Phosphatidylcholine showed an increment in oleic and palmitic acid content and a concomitant decrease in arachidonic acid. Phosphatidylserine showed a progressive increase while phosphatidylinositol showed a progressive decrease in all fatty acids. Eight-days post-cholestatic rats showed a marked increase in oleic acid, whereas linoleic, arachidonic, stearic and palmitic acids concentration decreased. Phosphatidylcholine showed a global decrease in its fatty acid content, except for oleic which is increased. Phosphatidylserine showed an increase over the two-days cholestasis fatty acids values, Phosphatidylinositol decreased in most fatty acids except in docosahexaenoic acid that recovered normal values. It was concluded that cholestasis produced significative changes in the fatty acid composition of the major phospholipids constituents of the microsomal membranes.
Introduction Hepatic bile flow can be interrupted by various 1976). When cholestasis means (POPPER& SHAFFNER, is produced, stagnant bile accumulates in and around the hepatocytes producing disturbances in various metabolic pathways. Some of these disturbances are thought to be mediated by membrane bound enzymes which are critically dependent upon their microenvironet al., 1985). ment (SINGHet al., 1982; BENGOCHEA Biochemical changes that occur in the endoplasmic reticulum were found to be closely related to changes in the dynamic state of the membrane. Under various pathological conditions the dynamic state of the membrane can be modified extensively enough to disturb & YOREK,1985). The basic cellular functions (SPEKTOR mechanisms of cellular injury produced by bile accumulation is still poorly understood. The aim of the present work was to study the effect of cholestasis on microsomal phospholipid fatty acids composition to clarify its molecular changes. Materials and Methods Male Wistar rats (body wt. 200-250 g) were fed with Purina Chow and water ad libitum. Extrahepatic cholestasis was performed under slight ether anaesthesia, by surgical ligation and secondary section of the common bile duct, proximal to its bifurcation. Cholestasis was maintained during two and eight days periods respectively. Then livers were excised and
homogenates were prepared using a 0.25 M sucrose medium, 1 mM EDTA pH 7.4 (HEIRWEGH eta]., 1972). Microsomal fractions were obtained by ultracentrifugation (DE DUVEet al., 1955).Normal rat livers were processed to determine control values. Lipids from microsomal fractions were extracted according to FOLCHet al., 1957. In order to separate the different phospholipids, a T.L.C. method was employed using chloroform, methanol, water, triethylamine (30:34:8:35) as developing system. Markers were developed simultaneously. Once separated, phospholipids from each different group of rats were pooled and its fatty acid composition was determined by G.L.C. after direct transesterification (LEPAGE & ROY, 1986). Fatty acid methyl esters were separated at 180°C on a 180 crn column of a 10% SP 2330 on chromosorb W-AW-PMCS (100-200 mesh). Detection was performed by flame ionization. Five rats were used in each group. For statistical analysis a Student’s t test was used to compare groups; P
Archives Internationales de Physiologie, de Biochimie et de Biophysique, 1992, 100, 109-111
R e g le 29 janvier 1991.
Changes in microsomal phospholipid fatty acids composition in cholestatic rats BY
L. A. BENGOCHEA, C. B. OUVIRA, A. PAVESE and A. LEMBERG (Catedra de Fisiopatologia, Facultad de Farmacia y Bioquimica, Universidad de Buenos Aires)
Archives of Physiology and Biochemistry Downloaded from informahealthcare.com by Chulalongkorn University on 12/29/14 For personal use only.
(1 figure)
In the rat, the effect of the bile duct ligation on liver microsomal phospholipid fatty acid composition and on phosphatidylcholine, phosphatidylserine and phosphatidylinositol pattern were studied. After two days of cholestasis, microsomal phospholipid fatty acids showed a decrease in linoleic, stearic and arachidonic acids and an increase in oleic and docosahexaenoic ones, as compared to controls. Phosphatidylcholine showed an increment in oleic and palmitic acid content and a concomitant decrease in arachidonic acid. Phosphatidylserine showed a progressive increase while phosphatidylinositol showed a progressive decrease in all fatty acids. Eight-days post-cholestatic rats showed a marked increase in oleic acid, whereas linoleic, arachidonic, stearic and palmitic acids concentration decreased. Phosphatidylcholine showed a global decrease in its fatty acid content, except for oleic which is increased. Phosphatidylserine showed an increase over the two-days cholestasis fatty acids values, Phosphatidylinositol decreased in most fatty acids except in docosahexaenoic acid that recovered normal values. It was concluded that cholestasis produced significative changes in the fatty acid composition of the major phospholipids constituents of the microsomal membranes.
Introduction Hepatic bile flow can be interrupted by various 1976). When cholestasis means (POPPER& SHAFFNER, is produced, stagnant bile accumulates in and around the hepatocytes producing disturbances in various metabolic pathways. Some of these disturbances are thought to be mediated by membrane bound enzymes which are critically dependent upon their microenvironet al., 1985). ment (SINGHet al., 1982; BENGOCHEA Biochemical changes that occur in the endoplasmic reticulum were found to be closely related to changes in the dynamic state of the membrane. Under various pathological conditions the dynamic state of the membrane can be modified extensively enough to disturb & YOREK,1985). The basic cellular functions (SPEKTOR mechanisms of cellular injury produced by bile accumulation is still poorly understood. The aim of the present work was to study the effect of cholestasis on microsomal phospholipid fatty acids composition to clarify its molecular changes. Materials and Methods Male Wistar rats (body wt. 200-250 g) were fed with Purina Chow and water ad libitum. Extrahepatic cholestasis was performed under slight ether anaesthesia, by surgical ligation and secondary section of the common bile duct, proximal to its bifurcation. Cholestasis was maintained during two and eight days periods respectively. Then livers were excised and
homogenates were prepared using a 0.25 M sucrose medium, 1 mM EDTA pH 7.4 (HEIRWEGH eta]., 1972). Microsomal fractions were obtained by ultracentrifugation (DE DUVEet al., 1955).Normal rat livers were processed to determine control values. Lipids from microsomal fractions were extracted according to FOLCHet al., 1957. In order to separate the different phospholipids, a T.L.C. method was employed using chloroform, methanol, water, triethylamine (30:34:8:35) as developing system. Markers were developed simultaneously. Once separated, phospholipids from each different group of rats were pooled and its fatty acid composition was determined by G.L.C. after direct transesterification (LEPAGE & ROY, 1986). Fatty acid methyl esters were separated at 180°C on a 180 crn column of a 10% SP 2330 on chromosorb W-AW-PMCS (100-200 mesh). Detection was performed by flame ionization. Five rats were used in each group. For statistical analysis a Student’s t test was used to compare groups; P
