The role of membrane composition in ATPase activities of cirrhotic rat liver: effect of silymarin.
The activities of Ca2(+)- and Na+, K(+)-ATPases were studied in liver plasma membranes from CCl4-cirrhotic rats and from livers of rats treated with silymarin in addition to CCl4. CCl4 chronic treatment produced significant decreases in Na+, K(+)- and Ca2(+)-ATPase activities; however, the animals treated with silymarin along with CCl4 showed no differences in ATPase activities as compared to controls. The lipid analysis performed in plasma membranes revealed increases in the cholesterol/phospholipid (CH/PL) and sphingomyelin/phosphatidylcholine (SM/PC) ratios in the cirrhotic group. Again, the membranes isolated from rats receiving CCl4 + silymarin showed normal CH/PL and SM/PC values. Considering that CH/PL and SM/PC ratios are related to membrane microviscosity, this study suggests that a lower fluidity of the membrane may be responsible for the observed decreases in ATPase activities in the cirrhotic group. Additionally, the role of silymarin to improve liver function in CCl4-cirrhosis can be attributed partially to its action at membrane level by preventing the increases in CH/PL and SM/PC ratios.
Muriel
P
P
Departamento de Farmacología y Toxicología, Centro de Investigacíon y de Estudios Avanzados del Instituto Politécnico Nacional, México, D.F.
Mourelle
M
M
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D002252:Carbon Tetrachloride Poisoning / Q000188:drug therapy / Q000201:enzymology*; D002462:Cell Membrane / Q000201:enzymology; D005419:Flavonoids / Q000627:therapeutic use*; D008099:Liver / Q000201:enzymology*; D008106:Liver Cirrhosis, Experimental / Q000139:chemically induced / Q000188:drug therapy / Q000201:enzymology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012838:Silymarin / Q000627:therapeutic use*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D005419:Flavonoids; D012838:Silymarin; D000251:Adenosine Triphosphatases; D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase